|RPG published by
Pagan Publishing and Arc Dream Publishing
|Rule System||Modified Basic Roleplaying System, GUMSHOE (The Fall of DELTA GREEN)|
Adam Scott Glancy
John Scott Tynes
|First Publication||1997 (Original sourcebook)
2017 (Standalone game)
2018 (The Fall of DELTA GREEN)
|Essential Books||Delta Green (Sourcebook for Call of Cthulhu)
Delta Green: Agents Handbook
Delta Green: Handler's Guide
Now we're on to the question: "What does Delta Green want from you?" Nothing short of the rest of your life. Delta Green wants you to pick up where I left off: doing what I've been doing for the last ten years. I've falsified official reports. Lied under oath. Planted evidence. Stolen and destroyed evidence. Stolen and destroyed federal property. Run illegal wiretaps. Abused the power and authority of my office. Gone AWOL. Committed arson, burglary, grand larceny, aggravated assault, battery, and killed. On three of those occasions, what I did was nothing short of cold-blooded murder. And all in the name of doing the jobs nobody else can or will.
Delta Green is a horror RPG based off of the Call of Cthulhu system. DG shares the Lovecraftian mythos with CoC, but most strongly differs in that it is specifically in modern times (where CoC was typically set in the jazz era).
Player Characters tend to be part of or somehow affiliated with government executive branch agencies (most typically law-enforcement or military) recruited into an officially disbanded clandestine group whose purposes was to investigate and neutralize occult and alien threats. DG is currently organized in a cell structure with 26 cells with three operators active at any one time.
So...basically, a bunch of the 'Federales' grouped up to make a highly illegal terrorist organization to fuck up aliens and occultists.
Did we mention that there's a legit government agency called Majestic 12 who are in bed with what they think are aliens? So yeah, terrorists.
- 1 What does Delta Green offer?
- 2 Basics
- 3 The Setting
- 4 Recent Happenings
- 5 The Big Players
- 5.1 Delta Green
- 5.2 Majestic 12
- 5.3 The Greys (And the Mi-Go)
- 5.4 Great Race of Yith
- 5.5 Lloigor
- 5.6 Karotechia
- 5.7 Deep Ones
- 5.8 The Cult of Transcendence
- 5.9 PISCES
- 5.10 GRU SV-8
- 5.11 The Fate
- 5.12 Tiger Transit
- 5.13 Ghouls
- 5.14 The Hastur Mythos
- 5.15 M-EPIC
- 5.16 Saucer Watch
- 5.17 Phenomen-X
- 5.18 Other various cults
- 6 External Links
What does Delta Green offer?
It's important to mention that both the setting and the system fix many problems underlying with the standard Call of Cthulhu game, here's your average CoC game:
- PCs are a bunch of randos of random occupation/social class.
- They don't know each other and have nothing in common except what's about to happen to them, but happily stay together for no good reason.
- They investigate when they should be running the hell away.
- Luckily, investigation is made easier because NPCs are perfectly willing to talk to them for no good reason.
- Once they start dying, replacement PCs come from out of nowhere and are instantly trusted for no good reason.
- And once they're done dealing with whatever, horrible things keep happening to/around them for no good reason.
Delta Green fixes all of this.
- PCs are government agents and members of the DG conspiracy.
- They don't have to stay together, but they are brought together at times by higher-ups because they're part of a cell.
- They investigate because they're DG agents and feel like they're the only ones who can help stop mythos incursions into reality.
- They're the government, so it's easy enough to have or fabricate a reason for people to talk to them.
- Replacements are DG agents or friendlies, and are somewhat trusted for those reasons. And if they're not, there's a certain amount of X-Filesy paranoia built into the setting.
- Finally, they're sent to the scene of weirdness by A Cell, so it doesn't have to come to them.
Delta Green is based on the Call of Cthulhu ruleset, with some unique mechanics:
- Lethality rating: Basically, no weapon or attack deals more than 2d10 damage. However, weapons such as cruise missiles have a "lethality rating" of between 10 and 90 percent. If that 2d10/d100 roll is less than the lethality rating, the targeted enemy dies instantly. This saves you from rolling a bucketful of dice to determine exactly how hard you hit that Dark Young with a jury-rigged antitank mine.
- Bonds: Each Agent gets a number of Bonds which depends on their background. Bonds are basically friendships or relationships with NPCs (and potentially PCs) that act as both a character-expanding tool for players and a sanity-regulation mechanic.
- When things go terribly wrong on Nights at the Opera, there is a chance that Agents begin to develop bonds with each other (at the expense of already-existing ones).
- When Agents lose SAN or go temporarily insane, they can spend 1d4 from both Willpower and any Bond to try to repress the madness ("I'm doing this for my kids/wife/friend!"). During between-mission vignettes, the results from this coping mechanism should be played out.
- Some skills and mechanics, like Spot Hidden and Education, have been rolled into other ones.
- PCs are generally more capable in combat; but many many things in the DG universe will hand Agents their asses.
- PCs, to a certain extent, can also call upon the resources/influence of the organization they work for.
- Depending on their creativity and ability to come up with "mundane" reasons (you've got to be hella good to divert a B-52 wing and convince them that the town filled with worshipers of the Deep Ones is just a mock city they're supposed to make practice bombing runs on.)
- As a PC typically won't have official sanction, this typically involves a lot of lies, inventing evidence, intimidation, and other various tactics to make sure Deputy Fife doesn't make any calls to check your credentials.
- The last point depends on what era you're working in as well.
Essentially, the modern world, but where Cthulhu definitely dreams (as opposed to ours where it's only a distinct possibility). Add into that a boatload of secret cults, secret societies, secret governmental agencies, eldritch abominations, a lot of insanity, and you're almost there.
Oh yeah, notice how we didn't say anything about aliens? Yeah, so those "aliens" Majestic-12 are working with, they're just fungoid constructs by one of the many eldritch abominations floating around who are doing nasty things to humans for their own purposes.
If you're Handling a Delta Green game, there are three main eras they can be set in:
The Classic Era (1928-1969)
This is the era where Delta Green is an official organization within the U.S. government, founded after information about the Innsmouth raid makes its way to the Department of Naval Intelligence. Featuring the ONI P4 division going in a Deep One killing-spree world tour, DG fighting against Karotechia in World War 2 and Delta Green fighting in Vietnam, slowly losing it's prestige until it's disbanded after the failed Operation OBSIDIAN. Sadly not too many scenarios are set in this era (perhaps due to the overlap with Call of Cthulhu.)
The Fall of DELTA GREEN is set in this era, although it's focused on Delta Green operations in Vietnam and Indochina in the 60s.
The Cowboy Era (1970-2001)
After the disastrous OBSIDIAN raid, the powers that be disbanded Delta Green. From 1970 to 1994, the organization worked as a "good ol' boys" model, with old agents occasionally getting together to deal with issues. In 1994, former agent Lt. Gen. Reginald Fairfield was assassinated by MJ-12 NRO Delta operatives, which provided the influence to Professor Joseph Camp (Agent ALPHONSE) to create the cell structure that existed from 1994 to 2002.
This is known as the "Cowboy Era" because it basically consists of old Delta Green veterans and new recruits fighting the Mythos without any sort of official sanction.
The original 1996 sourcebook is set in this era.
The New Era (2001-present)
After the September 11 attacks on New York City, the U.S. intelligence community began a major reorganization which saw MJ-12 (which had been struggling to contact the Greys for some time) disgraced and eventually taken over in a coup by Delta Green (detailed in the novel Through a Glass, Darkly), the US government then unified the remnants of MJ-12 and the Cowboy Delta Green into a new, "official" and authorized operation that uses the war on terror as a cover to act against the mythos. However, some old-school agents refused to "come in from the cold" and formed their own faction, so both Program (official) and Group "Outlaws" (unofficial) games are possible in this era.
The setting of the 2016 standalone RPG.
After a 6 year drought of new rulebooks, Delta Green was relaunched with a highly-successful Kickstarter in late 2015. A new complete rulebook came out in 2018, with the promise of further supplements and campaigns to flesh out the parts of the setting covered by the old splats.
The setting is also significantly revised.
- MJ-12 is no longer active as an independent entity, having been destroyed/taken over in a coup by agents of Delta Green and dissident MJ-12 operatives. What was left of the 'Steering Committee', the exalted leadership hierarchy of MJ12, either fade into obscurity or merge into the clandestine and influential March Industries defence contractor. Remaining external assets are integrated into the NSA or private sector.
- Delta Green itself is now split between the Program and the Outlaws, with the former being the "legal" government organization and the latter being the old agents that were (rightfully) suspicious of joining up with what looked a lot like their greatest enemy.
- The Karotechia is gone, having been wiped out in 2001 at the hands of the only known joint Delta Green/MJ-12/GRU SV-8 operation.
- The Mi-Go have been silent since the late 1990's, abandoning their puppet constructs 'the greys' and cutting off all channels of communication to MJ-12.
- Stephen Alzis departs from The Fate headquarters in Club Apocalypse and is not seen again. The Lords of the Fate splinter and war among themselves for control of the occult criminal syndicate purportedly by Delta Green intervention. In the aftermath of the conflict, the corporate shell company that owns Club Apocalypse is acquired unexpectedly by a little-known Chinese investment consortium called Star Holding and Investment.
The Big Players
As with any clandestine organization, their history is all kinds of jacked up. DG has existed in some capacity or another since 1928 as a response to the crazy crap found during a raid on a Deep One Cult located at Innsmouth, MA. It is interesting to note that the raid on Innsmouth ended with everything even remotely suspicious being thoroughly dynamited, which remains Delta Green SOP to this day. They changed names a few times and were handed around to various parts of government for a while before they finally coalesced as "Delta Green" which wasn't so much a name for them, but for the classification and access level required to actually know anything about them; however it eventually came to serve as a name, official or not.
During their later years as an official organization, they acted without much of a command structure with people who were in the know just calling each other up anytime they ran across something DG should handle, and then they handled it with little to no oversight. When they screwed up royally in Cambodia during a 1969 raid that resulted in most of the people who participated dying, they finally gave the likes of Majestic 12 and other political enemies an excuse to finally disband them.
This didn't sit well with some portions of DG who quietly got together and said we're going to keep at it. What little oversight and control there was before no longer existed, and as a result, many DG operatives executed their self-appointed duties with extreme prejudice. Eventually, one of the DG leaders started looking into MJ-12, pissed them off to the point where they sent their own operatives, DELTA, to assassinate him. This then leads to the decision to reorganize DG into the cell structure used by the Outlaws to this day.
In and around the turn of the millennium, several things happened:
- ADAM is killed in a Karotechia ambush (accidentally) orchestrated by former operative Captain Forrest James, a.k.a. Agent DARREN.
- ALPHONSE goes out in a blaze of glory by summoning a tiny aspect of Azathoth to kill himself and an NRO Delta strike team, leaving just ANDREA (the one who nobody knows exactly who it is) in charge.
- The remaining members of the group get together and basically conduct a coup against MJ-12, with former MJ-3 director Gavin Ross collaborating and eventually taking over as ADAM.
Not everyone is happy with this turn of affairs, including a whole bunch of Delta Green agents who refuse to "come in from the cold" and become legitimate. Which caused a schism between two different groups, each claiming to be Delta Green. The Handler can choose which factions the Player Characters will be part of, both offering different playstyles and themes.
In the 90s, MJ-12s Counterintelligence Director Gavin Ross got very disillusioned with Majestic, as it had become a cargo cult that worked for the sake of Grey technology instead of protecting the United States. Ross and his aide "Captain John R. Smith" (Actually ex-DG agent Forrest James, Agent DARREN) planned a coup on MJ-12s leadership; this coincided with the apex of the Majestic-Delta Green war, 9/11, and the withdraw of the Greys. James and Ross were able to take over Majestic and reform it into something that could protect the American public. Majestic was moved into the auspices of the NSA and the clearance code DELTA GREEN was reactivated.
The Program, as how insiders nicknamed it, is both the "official" Delta Green and the continuation of Majestic-12. It has larger access to the NSA's black budget, official cover for its agents, Majestic's research capabilities, a CIA psyops unit used to convince people any supernatural thing uploaded in the internet is fake, and literal military forces in the form of their "asset recovery team" CORAL NOMAD, a pararescue unit "borrowed" from the US Air Force and a continuation of MJ-12's Operation BLUE FLY, March Technologies as well division inside government agencies such as DARPA or the USAMRIID serve as their advanced research division, and they can provide covers for their agents so people outside The Program can't ask too many questions when investigating. The Program employs a more united and organized structure than the old illegal Delta Green, which makes more capable to cover and investigate all the weird shit going on.
If The Program looks suspiciously too similar to Majestic, remember it's only the same organization, but now under a new direction.
A Program game is about abuse of power, luxury of resources and staring into the abyss. You may have the people and the resources but that's minuscule in the face of the cosmic horrors of the universe.
When Agent ALPHONSE went out in a blaze of glory after a Majestic attack, Donald Poe (Agent CHARLIE) found himself in possesion of all of A-Cell's resources. With no passing the torch and no mentorship from ALPHONSE, he was now the leader of Delta Green. At the same time, The Program was activated with Delta Green's files and attempted to recruit every old member of the Conspiracy. Some refused, seeing that the Program is just the continuation of the organization they fought for years and remained illegal in the conspiracy they always knew. The leaders of The Program gave them the name "The Outlaws", the people inside of it simply refer to themselves as "Delta Green".
In reality, whatever remained of this organization is utterly fucked up. The Outlaws still use the old Cell-based structure, but they have been very dysfunctional in their organization. They are very small compared to the Program, without any extra resources that the Program might have, and recruitment rates are very low, not enough to replace the agents that are either dead or too old for this shit.
Playing a Outlaw game is about fighting a losing battle, where paranoia reigns supreme and the situation is somehow worse then it was during the late 90s and the Cowboy years.
Majestic 12, or MJ-12, was formed in response to the highly publicized Roswell Incident where an alien craft crashed into the deserts of New Mexico. Beyond taking charge of the craft, bodies, and survivor, MJ-12 was responsible for covering the incident up and keeping knowledge of aliens from coming to the attention of the public. It was originally formed with some former members of Delta Green who did not necessarily agree with DG's policy of just destroying everything they came across, wanting to keep some for study and possible use against the USA's enemies. For the most part, DG and MJ-12's responsibilities did not seem to overlap, but from the beginning, there was a basic and divisive difference in philosophies.
Over time, MJ-12 managed to finally end up making contact with what it thought were alien life forms and agreed to cover up their activities on earth in exchange for technology which they slowly filter into the market (making themselves rich) and a vague promise on the part of the Greys (the "aliens") to be put in touch with other intelligent species throughout the galaxy.
The 12 of MJ-12 comes from the 12 members of the steering/oversight committee that runs all of the projects and subprojects that fall in MJ-12's jurisdiction. Each of the 12 members is head of a specific project that relates to either interaction with the Grays, covering up the Grays' activities on earth, and/or exploiting the technological revelations.
Over time, this relationship with the Greys has soured for some members of MJ-12, but they cooperate out of fear of the superior technology that humanity is essentially defenseless against (a nuclear weapon is unable to scratch the material they use to make the hulls of their craft). Other members are blinded by the technological opportunities and opportunities for personal gain.
As MJ-12 is a proper black governmental agency, they have nigh on unlimited access to various resources, be they the finest minds, money, research facilities, etc. They do maintain their own group of operators whose primary task is to use techniques first developed in the CIA's MK-ULTRA and further refined with the "alien" technology and practice to cover up any activity of the Greys. While strongly preferring non-violent means (which are generally less complicated to implement) they can call into play highly capable combat units, such as BLUE FLY, an unit of Air Force paratroopers which basically act as X-Com, and NRO Delta, a secret unit inside the National Reconnaissance Office (Itself a secret government agency that manufactures and operates spy satellites) formed by CIA, NSA, DIA and SOCOM operators which act as Majestic's cleanup, coverup and wetwork division.
MJ-12 is aware of DG's continued activities, but mostly does not fully consider them a threat. Some members of MJ-12 see DG as a possible way to strike at their enemies within MJ-12 or even possibly the Greys themselves.
What could be considered the continuation of MAJESTIC-12, March Industries originally started as a cover industry to Majestic's research, but after their collapse, many of Majestic's assets, researchers and even four members of the steering comittee ended up in March. They are too big to be opposed and disbanded, instead Delta Green made a partnership so they can provide research, both now live in an uneasy truce.
Since they are controlled by the old leaders of MJ-12, they have since bidding their time to return and retake their position, while some of their members have ties with GRU SV-8.
The Greys (And the Mi-Go)
The Greys are the supposedly alien race who are exploiting the government of the United States of America. They are actually essentially puppets of the Mi-go (an extension of Yuggoth). Long story short, on their travels around the universe, Humanity is the only race the Mi-Go found that has a "Epistemically Diploid" brain; it's both rational and irrational, allowing to humans make guesses that do not fit a logical extrapolation from theoretical models (in other words, gut feeling). And it's often that those irrational leaps of logics are correct, which is utterly unnerving for the otherwise ultrarational Mi-Go, and they're seemingly impressed with our growth from radio to nuclear weapons. However, our only brief Humanity Fuck Yeah moment in the Delta Green (Or even in Lovecraft's stories) is cut short, the Mi-go know that all hell is about to break loose because the foretold end times are just around the corner. Among other things, they have a goal to learn everything they can before they get the hell away from the Earth (to where remains a question).
To these ends, they had to speed up the research they were doing on humans but wanted to do such in a way that wouldn't get every government in the world finding and eliminating them. So, they made up the Greys who they control via a strange sort of telepathy and set things up in such a way that they now have the most powerful government on the planet cleaning up their messes willingly for a few trinkets.
After the Mi-Go fucked off from Earth and the Greys ceased contact, it's "Main Mythos antagonist" spot was taken by The Great Race along with the Lloigor.
The Great Race is a mysterious race from both the past and the future, their main goal is to ensure they can mass mind-snatch with another beetle-like terrestrial race to live on Earth millions of years after humanity died. With their mind-snatching powers and quasi-temporal omniscience, they frequently change minds with humans during history to study their surroundings and further their plans, often followed by human servants known as "The Motion".
They are playing 4D Chess (In the literal sense, since time is the fourth dimension) in a temporal cold war against their arch-enemies the Flying Polyps but also the Llloigor, which seek to estabilish in Earth a human empire known as "The Cruel Empire of Tsan-Chan", a large and extremely dyspotic Empire standing on the end of human history after the Great Old Ones woke.
The other metavillans of the updated setting, along with the Great Race of Yith,
The Lloigor are a race of living psychic vortices coming from the galaxy of Andromeda, and an entire race of That guys. They feed and exist solely to cause suffering and pain, and are generally such dicks that even such moral luminaries as Nyarlathotep and Y’golonac think they are a bit much. They also can become dinosaurs, cause metaphorical and literal cancer, and live in rocks.
After they came from Andromeda, they settled on the now sunken continent of Mu and formed a huge empire with a caste system of slaves and sorcerers. After Mu was sunk, their power dwindled and they spread through Earth where they continue to be assholes, but on a smaller basis as they are slowly recovering. Where there's a Lloigor rock, they start spreading their hate, feeding on agony, creating cults of unwitting supporters (if the PCs' standard operating procedure is callous violence, they are already part of the Lloigor Pattern) and spreading as both physical cancer (by infecting people with cancer but extending their lives with immense pain) as well a "metaphorical" cancer through societies and bureaucracies, creating conflict and division. They apparently can also transform into giant dinosaurs when their power is strong enough, which might have inspired the old legends about dragons.
Their endgame is to recover their power and create an empire on Earth where their cruelty and sadism influences all of humanity.
The Kuen-Yuin are mysterious and ancient cult of Chinese sorcerers who have existed for millenia, influencing Chinese history since the times of the quasi-mythical Yellow Emperor: manipulating imperial politics through assassinations and a good dose of magic, strengthening the power of the emperors who supported them, and causing the various dynasty changes and warlord eras. They are lead by immortal sorcerers who are the old Priest-Kings of the empire of Mu, made immortal by the powers of the Lloigor (known to them as the Xin).
The Kuen-Yuin operate on the concept of sadism for sadism's sake, causing as much pain, despair and destruction as possible and leaving a lasting impact. They seek to wake up Cthulhu, as they are the "deathless ones in the mountains of China" who control its worldwide cult and all of their plans converge around creating the Cruel Empire of Tsan-Chan, an empire that will exist in the year 5000 after the Great Old Ones rise and humanity will live only under the totalitarian and sadistic control of the Kuen-Yuin and the Xin. Ironically, after the Cultural Revolution Mao Zeodong declared "magic" as superstitious and counter-revolutionary, the Kuen-Yuin were purged and mass-executed by the Communist government, forcing most of their ranks into exile within the rest of the world. This is not necessarily a good thing.
Imagine liches. Make them Nazis. Oh, and there's just three of them, but they've got a lot of underlings. Stick them in South America. You've now got the Karotechia. One has to stay in a fridge (like Dr. Muñoz from Lovecraft's Cool Air), one is a merc who just enjoys being a merc (who's also is a cannbibal, he has powers similar to a Ghoul, making him still young despite his old age), and one thinks the ghost of Hitler is telling him to start up the 'Fourth Reich', but this time to base it off of occultism (and said ghost is just Nyarlathotep being an asshole). The last one is crazy as fuck and the other two are scared to death of him, so they play along.
Of course, three guys can't do all the work alone. So they have covertly achieved control of ODESSA and Die Spinne (networks of escaped nazis), neo-nazi organizations, white supremacists, anti-zionist jihadis, mercenary groups, drug cartels and have even brought back old figures of the nazi regime as zombies, all of this in order to create their "Fourth Reich".
As of the new millennium they are dead with a capital D, having been totally wiped out in one of the extremely rare joint missions between the MJ-12, Delta Green, and GRU SV-8.
Fish people that can breed with humans to make strange hybrids that look human until a certain age when they change and turn into fish people and go off into the water to live with the greater Deep Ones. Ceremonies of worship are orgies of violence and well, orgies. Due to shenanigans by Delta Green, namely setting up pillboxes and landmines, then casting Call Deep Ones, creating a scene that makes the D-Day landings look like a drunken scuffle in the pub car park, said spell no longer works. As such, the vast majority of them have determined the surface world is now more trouble than it's worth, and only very isolated enclaves remain on the surface.
Black Cod Island
The oldest and most significant Deep One colony, Black Cod Island is inhabited by a infected offshoot of the Haida of the Pacific Northwest. From the outside they are seen as a village of fisherman, famous as an anthropological curiosity seen as a Haida offshoot that has more focus on the ocean and are known as a quaint "model settlement for native-americans". In actuality they were founded in 1555 by exiles from the mainland, who were expelled after the Haida united to destroy their original village, worshipping a primal Deep One named "He-Who-Swims-With-Corpses". As they are so old, the hybrids from Black Cod are much worst then the Innsmouth hybrids, since they have been breeding for longer and the resulting offspring are more powerful.
The Exalted Circle is a urban and modern branch of Innsmouth's Esoteric Order of Dagon, formed by rich industrialists and landowners who used the pact with the Deep Ones to fill their own pockets with the gold and eliminate their enemies with magical powers. Their influence brought the attention from the Cult of Transcendence (see below), who they thought the Circle were America’s “occult overlords”, they did a coup which brought the Circle into the fold of the Cult of Transcendence, now placed under the See of Greed. Now the Exalted Circle provides the Cult with power, influence, wealth and connections to the Deep Ones.
After the desintegration of the Cult of Transcendence in 2012, the Exalted Circle went indepedent, mostly focused on getting more money instead of bringing the end of the world.
The Cult of Transcendence
Essentially this setting's Illuminati. They started as an occult conspiracy dedicated to secretly ruling the world through magic. This failed repeatedly, so they reorganized as a dedicated cult of Nyarlathotep (who oversees the cult personally). They're run from an extra-dimensional mansion that's kind of located in Sweden. They also maintain various front organizations throughout the world, secretly influencing mankind to bring about the return of Cthulhu. As people progress up the cult's ladder, they're initiated into more and more of its mysteries, gradually becoming less human, until they turn into generic tentacle monsters. Through its various front organizations, the cult has access to everything from stolen Yithian technology to a massive empire of nightmares carved out of the Earth's Dreamlands. Possibly the most dangerous and evil organization in the DG world. Their shtick is that they would create intricately complex conspiracies but always fail miserably in their operations and their shady council of vagueness would just say JUST AS PLANNED while planning their next step.
Collapsed on itself in the 2010s due to infighting and getting too high off their own Mythos supply. Most of their old sub-groups became indepedent to enact their own plans.
Delta Green's British counterpart, the Paranormal Intelligence Section for Counter-intelligence, Espionage, and Sabotage. It was originally founded during the First World War as MI-13, where they dabbled in psychic talents and ESP, but suffered a severe setback in 1925 when they not only lost most of their budget to a cash-strapped British government but many of their "talents" to a bizarre series of mental collapses, courtesy of a partially awakened Cthulhu.
MI-13's big break came during the Second World War, when the current head, Major David Cornwall, placed a sealed premonition by one of their remaining "talents" as to how the defense of France would go in the hands of Prime Minister Winston Churchill. Opened by the latter the day after the evacuation of Dunkirk, the shockingly accurate prediction convinced Churchill that Cornwall and MI-13 were the real deal. Thus PISCES was born and immediately began work to undermine the Karotechia, who were working feverishly to use supernatural forces to aid the Nazi government. The first joint Delta Green/PISCES operation occurred in 1942 when agents (with the aid of French partisans) were able to sabotage the Karotechia's negotiations with the Deep Ones. Though the two agencies were nominally allies, their radically different philosophies led to distrust. By the 1960s, Delta Green and Pisces no longer worked together, which turns out to be very fortunate for the former.
In a 1968 raid on the English town of Goatswood, several PISCES agents were infested by the cerebral parasites known as the Shan. Over the next twenty years, the Shan gradually took over the entire network, placing an infested member in charge of PISCES in 1988. Though they only currently control about ten percent of PISCES personnel, it's the ten percent needed to direct the entire organization. Though they still continue counter-Mythos ops, it is for the security of the Shan's hidden temple and their eventual goal of leaving Earth rather than for the safety of England.
The Russian counter-paranormal agency, founded after the Red Army found ghoul cults feeding on the corpses of the Russian Civil War (Really could've just been the peasants but better safe than sorry). During the Great Patriotic War, they clashed many times with Smersh, the NKVD's paranormal section, as well as destroying Karotechia projects to resurrect the dead. After the war, engaged in a mad scramble to destroy Karotechia information as Smersh tried to collect it. Later released Delta Green operatives who had been captured by the Spetsnaz to destroy Stalin's life-extension projects, and destroyed Smersh in a bloody coup. Since then, they have tried to steal things from MJ-12. They allied with Delta Green and MJ-12 to destroy their common enemy of Karotechia once for all.
In the updated setting, the real-life restructuring of the GRU in 2008 led to the SV-8 begin "discovered" in 2010 by none other then Putin himself, the Kremlim was seemingly impressed with the "alien technology", kicked out the cadre of old officers into a more controlable younger generation and they were given a lot of budget, a significant improvement from their old underfunded and understaffed status from after the fall of the Soviet Union to a powerful organization. This came with a cost, however, SV-8 has deviated from their original mission, from defending Russia they became part of the Kremlim's tool to expand Russian power into the world using the supernatural.
Occultists based in NYC. The Fate were a group of very powerful magic users who contract out to criminal organizations. To those criminal organizations, they are known as The Network (the arm that functions as a sort of public face for The Fate). Mostly they do this to have access to professional thieves and other less than legal vectors for acquiring specialty items for their rituals, information and the like. They were led by a dude named Stephen Alzis who is rumored to actually be Nyarlathotep, and was (is?) certainly more than human. They have a lot of connection as well to a nightclub in NYC named Club Apocalypse, where the Mythos-influenced metal band Charnel Dreams plays.
As of the new millennium, things have gone tits-up for the Fate. First, Nyarlathotep stopped answering their calls; second, Alzis vanished to parts unknown. Seeing the opportunity to take down their confused enemies, Delta Green engaged in a series of assassinations which left most of the Fate's operatives dead. The ones that didn't get whacked largely grabbed whatever artifacts they could and headed for the hills.
During the 1960s in Vietnam the CIA had this amazing idea of arming the Tcho-Tcho to fight the Communists, not unlike the Hmong, the Yao or the Montagnard, except the fact that they were the fucking Tcho-Tchos. Even brighter idea was to give them the ownership of a a dummy company named Tiger Transit, used in "deniable" operations, like contraband through Indochina or Nicaragua like Air America, except its controlled by the fucking Tcho-Tchos.
The Tcho-Tchos themselves have immigrated to America, based mainly in Chicago. They used their Tiger Transit assets to create an hybrid between an occult cult and crime syndicate, known as the "Tong Shukoran". They have introduced unnatural drugs into the US market such as the Liao, a more diluted and refined version called Reverb, and another mixed with cocaine known as "Coca Loca".
Around the 2010s, after years of fighting the Tcho-Tcho, the Outlaws successfully dismantle their cartel and are able to freeze most of Tiger Transit assets, then The Program comes and steals their air fleet for themselves. Some Tcho-Tcho drugs, such as Reverb, are still being distributed in the drug market.
Classic Lovecraft monster: greenish pallor, rubbery skin, canine muzzle, pointed ears, hooflike clawed feet, can disguise as humans and of course, eating human flesh for breakfast. In Delta Green, however, they are usually a little more friendly (don't rely on it too much unless you want to become lunch) and divided in various factions.
Keepers of the Faith
A faction of Ghouls living in the underhalls beneath New York. Existing since the 17th century, they hid in the vast network of tunnels and passages beneath the city, where they isolated themselves from society in order to continue their cult of Mordiggian, while recruiting from the homeless population of New York, so they might be the inspiration behind the homeless "mole people" urban legends.
Otherwise they are suprisingly chill, they only eat dead bodies they steal from the graveyards and want to be left alone, so they have an uneasy truce with Delta Green. Their big problem (and the reason they might cross with DG) are the "Heretics", new recruits that become mad with the hunger of human flesh and fuck off from the cult to hunt down some actual living human flesh. This is against the Mordiggian way of doing things and so the young Ghoul is branded a heretic and hunted down, but it can rack up a lot of kills and attract certain "government agents" looking for a "serial killer".
Based on new Orleans, a family of aristrocratic Ghoul who came to the city from Haiti just after the slave rebellion. They became very wealthy and turned into the city's elite, enough to control the city's mortuaries and funeral parlors for an easy supply of food. With such an easy life, they shedded their faith in Mordiggian and became refined new-age Ghouls. They prepare human flesh in fine cousine instead of eating rotten and live a life of decadence. They also became proficient in magic/hypergeometry and can turn people into Zombies, a mix between both classic voodoo and "living undead" varieties.
When Hurricane Katrina happened in 2005, the city flooded and hundreds drowned, without any authority or law and order to stop them, a feast of corpses was available for the DeMonte. The Outlaws basically called every agent possible and sent deathsquads into the town to hunt down the Ghouls vigilante style, resulting into the clan almost begin wiped out. They might also have gotten some innocents too but woops, that's law enforcement agents for you.
The Hastur Mythos
In Delta Green, takes a very different approach to the Hastur mythos. Instead of the version Call of Cthulhu uses that is based on August Darleth, Delta Green instead base Hastur on the original source material: Robert W. Chambers' The King in Yellow.
Hastur is not a god or a great old one, Hastur has no personality, no individuality, no sentience. Hastur is the force of entropy, the cosmic principle which destroys order, everything from the quantum to the cosmical level is influenced by the entropic force of Hastur. When places and people are influenced by Hastur reality becomes relative to the observer: buildings shift, paintings change, lights flicker, statues mutate and time flows differently. Some places where the infection and corruption is strong enough, it will be pulled into Carcosa, a bizarre city that exists outside our reality, an enternally changing city where thought, ideas, dreams become real, reality is constantly rearranged when not looking, impossible geometry becomes possible and dreamlike logic becomes fact. Anything is possible. Carcosa is "ruled" by a mysterious figure known as "The King in Yellow". An avatar which appears where Hastur's field of influence heightens: vice and melancholy, the social entropy disintegrating human order.
Less of a cult or a secret society, the Lonely are a bunch of lonely people who shitpost on the internet. One day they encounter a figure named "CptnSnshn" (Captain Sunshine), a shitposter master who has the uncanny ability to find isolated people in nearly any internet subculture, CptnSnshn then reinforce and amplify their loneliness and resentment, eventually a mysterious book appears on their room, a retelling of The King in Yellow but in a familiar context of the reader. After reading the book, they become members of The Lonely, and as they progress, they start "spreading" their loneliness, and then dissapearing from existence. Or they become "The Grim", blaming women/society/jews for their loneliness and becoming stalkers and bullies, and some Grim become "The Furious" who decide to go in a lone crusade against society, becoming mass shooters and mad bombers.
In actuality, "CptnSnshn" is a Phantom of Truth, an avatar of King in Yellow, representing the entropy and destruction of social relations.
Canada of all countries have their own version of Delta Green, and actually quite old, predating Delta Green, PISCES and GRU SV-8, founded in 1903 by Mounted Policeman to fight groups of aboriginal cultists as the "Detachment M", they were sent to Europe to help PISCES during the Second World War and were briefly disbanded, recreated in 1946 as M-EPIC. M-EPIC investigates paranormal and occult phenomenon, acting as a support wing for the RCMP under the cover of the "Environmental Policy Impact Commission" (EPIC) of the Department of Environment, but it takes operators from all over the Canadian government, similar to Delta Green. They also differ from them due the smaller scope and willing use of sorcerers and magic (DG doesn't like to use it since it makes your brain figuratively melt).
A UFO research group that actually has some respectability by both being well funded (by some rich heiress who thinks she was abducted) and actually seriously researching reports of UFO activity, with emphasis on the word 'research'. They sometimes stumble on things MJ-12 would rather they didn't.
In 2000, they were both sued by the family of the rich heiress accused of misappropriating family funds, and then the local TV channel accused their leader Denton Schaeffer of possesing child pornography (Actually planted by MAJESTIC's NRO Delta). More lawsuits later and they went bankrupt.
Phenomen-X is a cable "paranormal" reality show that goes around "investigating" UFO sightings, conspiracy theories and other assorted paranormal phenomenon. While initially it was a bogus program, the crew of Phenomen X accidentally crossed Delta Green (as well Majestic, the Greys and the Mi-Go themselves) in Groversville during the events of the scenario Convergence, the sole survivor of the encouter, director Frank Carincola became obsessed with discovering the truth. He has been recieving calls from a mysterious informant as well, a supposed defector from "The Group", the secret US government agency he met at Groversville, with the informant pointing the crew into the direction of the supernatural.
In reality, the "mysterious informant" is both Majestic-12 and Delta Green manipulating Phenomen-X. MJ-12 uses them to expose and difficult Delta Green operations, pointing the spotlight at DG while Majestic remains hidden. Meanwhile, Delta Green uses Phenomen-X as "canaries in a coal mine", sending them first to see if there's an actual unnatural threat and if DG is needed.
The show started to suffer after the Delta Green-Majestic secret war, as the anonymous tips stopped coming and with them, their best stories. With low ratings and syndication contracts, the show became a low-budget web series in 2005. In 2010, they "envolved" into PX Penumbra, a website/brand where anyone (including ironic hispters) can upload their own paranormal recordings or shows and gain a little bit of revenue as well.
Other various cults
At any point, some other Cthulhu lore cult (such as the Cult of the Yellow Sign) may pop up and become a headache 'someone' had better deal with. All of the various eldritch powers will most likely make some sort of showing before the final curtain falls for some purpose, overt or otherwise. we mention the cults and not the powers themselves, because mostly the PC interactions will be with the cults...well, anyone sane would hope this to be the case...
- The Delta Green Mailing List - the oldest DG community in existance. It used to be hosted in Yahoo! Groups until that service was shut down, yes, it's that old.