"Fascism and Communism, like all other evils, are potent because of the good they contain or imitate. ...and of course their occasion is the failure of those who left humanity starved of that particular good. This does not for me alter the conviction that they are very bad indeed."
- – C.S. Lewis
The Chaos Gods are the gods which rule over the Realm of Chaos in Warhammer Fantasy Battles and the Warp in Warhammer 40,000. They love nothing so much as dicking with each other, except perhaps with their mortal followers, and literally each other (especially Slaanesh). Before they were gods, they were generally benevolent beings, when the Warp was a calm sea. Each one is formed by the emotions of living souls clumped together in the Warp/Realm of Chaos. Contrary to standard thought, they personify good attributes as well, and are powered as much by good as by bad. Even if said god started out entirely bad, in their eventual evolution as part of their natures, they will kill gods who represented entirely good things, and will gain not only their values, but their power by said value.
Be aware many of the gods' values will and do intersect. This is as much due to the chaotic nature of the gods as it is to the multitude of emotions that make up the living. For example: let's say you're literally obsessed with brutally murdering people and you get a real nice kick out of it. The act of spilling blood is gonna feed Khorne, while the ecstasy and obsessive sensation you get out of it will feed Slaanesh. So yeah, there's some overlap, in that an individual doing a certain thing, under specific circumstances, can simultaneously feed multiple Chaos Gods, but the God who was invoked (whether intentionally or no) upon when commuting the action will get the most power out of it (I.E: You killed someone for Khorne. While your ecstasy from the murder will feed Slaanesh a bit, your simple act of ending a life will feed Nurgle, your continued ambition to please the Blood God to earn his favor will also feed Tzeentch a bit, but Khorne gets the most since you offered that kill to him foremost).
According to the wikifags over at the Official Warhammer 40k Wiki, the Chaos gods were created and are sustained by the collective emotions of 'every sentient being of the material universe'; so not just the Milky Way, but every alien, both heretical and loyal, in the whole universe. This however probably isn't true, or rather it's just very bad wording, because if the Milky Way alone has all of these sentient races in it, then there's a safe bet that most other galaxies in the rest of the universe also have a multitude of sentient races too. And there are like, at least billions upon billions of galaxies in the observable universe, let alone the true universe which is likely many magnitudes larger. Based on what we've seen in the fluff, That many galaxies, filled with that many sentient lifeforms, all feeding only four Chaos Gods, would give said Chaos Gods so much power that they would probably have the capability to turn the entire galaxy (and many others) into massive Eyes of Terror at a simple scheming click of their heretical fingers. But of course, that hasn't happened (thank the fucking Emperor). Which probably means those wikifags are talking complete unadulterated bullshit, and in actuality, the full range of influence the Ruinous Powers have only extends to the area of the Milky Way and not much further. After all, a specific location in the Warp corresponds with a specific location in the Materium; your thoughts and emotions will have an effect (albeit very minor) on the Warp in your specific corresponding location, and the collective thoughts and emotions of a galaxy's population will only have an effect on that specific galactic area of the overall Warp. This essentially means the four Chaos Gods are completely confined to the Milky Way galaxy, because that's where the emotions that created and feed them are currently being felt.
So what does that really mean? Well, it means the Warp in the vast, cold, empty space between galaxies is calm as fuck, absolutely nothing like the infested shitty plughole it is right now in our home galaxy, because there's no sentient life and hence no chaotic emotions there to stir it up. However, this also means that if other galaxies out there have their own interstellar sentient species with a presence in the Warp, then those galaxies will have their own Chaos Gods [likely just analogous versions of the four (point five) we have, although it's also possible that the different emotions might be allocated differently for each galactic pantheon; Andromeda might have gods based on the seven deadly sins, for example] that reside there and are also confined to the area of their own galaxy. But who knows? Maybe each warp god is a reflection of the galaxy that birthed it , and the aliens that live in other galaxies there have actually got their shit together and all get along like best buddies in a setting that just oozes noblebright from every pore, and the Chaos Gods there aren't even called that because they're all so friendly and cushy to everyone and like to play vidyagames with each other and cracking open cold ones on a warm Friday night while watching The Batchelor. Maybe the Warp gods in most galaxies actually maintian contact with those in neighboring ones, and everyone just stays the fuck out of the Milky Way for the same reason most 21st century tourists stay out of Somalia. How sweet... I wonder what would happen if two galaxies, both with their own analogous Chaos Gods, collided. Would they just absorb each other into a new pantheon of four even-more-powerful Gods? Would they fight each other until one reigned supreme? Or would they get along like good ol' chums since they understand each other perfectly? Anyway, tangents.
Now that I say all of this, why the actual FUCK has no one decided to just up and leave the galaxy already?! It's a complete shithole! It's filled to the absolute brim with nothing but copious amounts of Grimdark and a whole host of things that want to murder, rape and eat you, not necessarily in that order. And it's still being filled up with that shit, both crawling out from under the ground and flying in from outer space to OMNOMNOMNOM the faces of everyone you both despise and adore. Even if you're lucky enough to escape the immediate crossfire, you're still likely to be part of a civilisation that completely smashes any feeling of worth or individuality out of you and treats you like just another cog in the machine of trillions of cogs. Just leave already, god dammit. What about Andromeda? I hear it's rather pleasant this time of year. At least compared to this literal hellhole. But it's probably not possible for the same reason why Big Bobby G and Lion-O couldn't simply fly over the Ruinstorm to get to Terra; if the space between galaxies is calm because there are no souls, that probably means there's no warp either, making intergalactic travel impossible. But this is just speculation. Plus, you need to be Necron-tier to get pass the nids off galaxy.
But then again, It is officially stated that Warhammer 40k and Warhammer Fantasy are both threatened by the same Warp with the same Chaos Gods, sooo....
Now, where were we? Oh yes, Chaos Gods. Ahem.
BLOOD FOR THE BLOOD GOD! SKULLS FOR THE SKULL THRONE! MILK FOR THE KHORNE FLAKES! BUTTER FOR THE POP KHORNE! Oh, sorry. In case it wasn't obvious, Khorne is the god of battle, martial honor, and oh yeah, BLOOD! Although primarily formed from hate and rage, bravery and honor are also thrown in the mix. Also in the mix are mercy (in particular, mercy for those too weak to put up a fight and be a challenge to kill. This is almost never shown in the fluff though, annoyingly), courage, regret, fear, athleticism, determination, daring, impulsiveness, and struggling onward in the face of any odds.
- Gender - DEFINITELY A MAN, AND DON'T YOU FORGET IT!!
I thought he was female?*BLAM!* *BLAM!* THAT'S DOUBLE HERESY!!
- Main Enemy - Slaanesh, as he considers him/her/them to be too frilly and really doesn't care about sensations, especially when they prolong the spilling of blood, to the point fluff wise it is distinctly pointed out he hates the priss even more than tzeench, going so far as to have slaaneshi and khornates have the hatred special rule against eachother.
- Bro god - Nurgle, although he doesn't seem to mind Khaela Mensha Khaine (they're probably the same thing, though), and he is rumored to be in a polyamorous relationship with Mork and Gork.
- Love Interest - Gork and Mork (see above). Valkia the Bloody (Canonically - yes, your brain is now broken).
- Dedicated Chaos Space Marine Legion - The World Eaters, other various chapters and bands of warriors dedicated themselves to him since. Also has IG-equivalent armies like the Blood Pact.
- Warriors of Chaos "Hero"/Chaos Tribe: Arbaal the Undefeated (ANGRY VIKINGS!! FUCK YEAH!!), Valkia the Bloody, Scylla Afingrimm (former warlord turned Chaos Spawn and still kicks ass), Hrafn Untam, Haargroth the Blooded, Skarr Bloodwrath. Khorne also has an entire Norse confederation especially devoted to him known as the Aeslingr.
- Sacred Number - 8 ("The eightfold path")
A Khornate Berzerker Heretic Astartes of the World Eaters Traitor Legion.
Nurgle is the god of filth, pestilence, decay, and generally being a cool dude (which are obviously related). Formed from despair and fear of death, his portfolio also includes acceptance and stoicism. Other values include inevitability, empathy, kinship, struggle, (familial) love, tradition, mercy, and memory. Nurgle is also notable for being the only Chaos god that cares for his followers whatsoever, bordering on love (in fact in 40k, he loves the Eldar goddess Isha so much that he chained her up and force feeds her his new diseases, because that's the only way he knows how to express love... yeah, love sucks
sometimes all the time most of the time). Also note that one aspect of him that is played up in the End Times is that he is in fact the god of life, only for him it means unrestrained, infinite life such as with pathogens and tumors.
- Gender - A (slob of a) man. A VERY fat, old one.
- Main Enemy - Tzeentch, the paragon of hope and change, in opposition to Nurgle's representation of decay and inevitability.
- Bro god - Khorne, mostly because Nurgle is the only Chaos god Khorne doesn't entirely hate.
- Love Interest - His joy and wife, Isha. Now pins for Alarielle, since he lost Isha to her.
- Dedicated Chaos Space Marine Legion - The Death Guard. Has tons of other followers like the The Purge (omnicidal wackos who have no problem using chemical and virus weapons on helpless populations), Apostles of Contagion (Zombie Plague aficionados), the Lords of Decay (utterly loyal Marines sent to die in the Eye, holy fuck these guys made a direct assault on the Solar System and won Pluto), and human IG armies like the rebellion on Vraks.
- Warriors of Chaos "Hero"/Chaos Tribe: Valnir the Reaper, old school champion of Nurgle; Festus the Leechlord (this guy used to be a doctor in the Empire; he's not even a Northman). The Crow Brothers of the Björnlings are especially devoted to him also (Festus leads these guys), the Glottkin, Gutrot Spume (a Nurglite pirate barbarian), the Maggoth Lords of Icehorn Peak. It could also be possibly argued (especially considering Age of Skubmar) that the Skaven Clan Pestilens is some sort of splinter cult built on worshipping Nurgle while thinking that they're worshiping an aspect of the Horned Rat.
- Sacred Number - 7 (though 3 is also a popular number)
- Please note that the above lore mixes both Warhammer fantasy lore and Warhammer 40k lore which, although the character is virtually indistinguishable, are not the same thing.
Slaanesh is the god/dess of pain, pleasure, and perfection... or, in other words, a god of emotions formed from emotions, not all of which are bad. In 40k (WHFB didn't elaborate how Slaanesh was born, so we can only assume he/she/they manifested normally like the other Gods), the an inherently psychic race called the Eldar created him/her/them by having so many damn orgies they tore space-time a new asshole (The Eye of Terror). Formed mainly from hedonism and excess, love and creativity are also attributes of Slaanesh. Other facets include perfectionism, obsessiveness, attention-whoring, jealousy, sensuality, DRUGS, empathy, self-expression, individuality, art, music, joy, and admiration (so quite literally the god of sex, drugs, and rock 'n roll!).
- Gender - Whatever you want it to be, sugar! In WH Fantasy you'll see illustrations of a lecherous old hag / old man / old bits-of-both; in WH40k depictions are of a young flamboyant hermaphrodite.
- Main enemy - The brutish Khorne, obviously. H-he never calls...
- Bro god - Tzeentch, although that's mostly because he's the least icky of the Chaos gods. His/her/their friendship with Nurgle is a bit questionable since he stole Isha during Slaanesh's proverbial and... literal raping of the former Eldar Empire, though it isn't shown anywhere that Slaanesh still openly detests Nurgle for that (Hell, their daemons temporarily joined forces once or twice). Generally the most open to working with the others.
- Love Interest - All of them. Still pines for Isha, and is depressed no one ever seems to love him/her/them back. Tries to tempt Khorne into raping him/her/them. Gave up on Nurgle after he got married. For a long time has been pining for Tzeentch of all people, but she can never seem to make him think she likes him as more than just a friend. Basically, she's the hot chick who got friendzoned by the nerd. But he/she/they won't give up!
- Dedicated Chaos Space Marine Legion - Emperor's Children. Also has others to call on like The Flawless Host (their drugs make Emperor's Children's look like baking powder), Violaters (these guys body sculpt themselves enough to make a Tzimisce well up with pride), as well as, again, various IG-equivalent armies.
- Warriors of Chaos "Hero"/Chaos Tribe: Sigvald the Magnificent (he really is quite magnificent...), Dechala the Denied one, former high elf maiden turned into near greater daemon level, Azazel, former bro of Sigmar, Styrkaar of Sortsvinear.
The Varg tribes serve him.NO WE DON'T. Likely that the Hung worship him/her/them, purely judging from their nomenclature. Also, Dark Elves, pre-retcon.
- Sacred Number -
A Slaaneshi-Heretic Astartes of the Emperor's Children Traitor Legion.
Tzeentch is the god of Just as planned and magic. Tzeentch is formed from paranoia and plotting, but also, amazingly enough, hope and ambition. Other values include trust, curiosity, dissatisfaction, aspiration, progress, knowledge, learning, protection, will, anarchy, and change.
- Gender - Always changing, but usually male or genderless.
- Main Enemy - Nurgle, because he symbolizes stagnation, a.k.a. refusal towards change.
- Bro god(dess) - Slaanesh, who isn't as brutal as Khorne and not as much of a lazy bastard as Nurgle. Plus, he/she/they're nice to little Tzeentch!
- Love Interest - Kind of wishes that the Deceiver, Cegorach, and the Emperor were.
- Dedicated Chaos Space Marine Legion - Thousand Sons, and basically no other Space Marine groups; only The Scourged are canonical non-TS-descendants who are dedicated to Tzeentch. Tzeentch also apparently doesn't have any IG-equivalent armies dedicated to him in particular (besides the Prospero Spireguard who are more like the Thousand Sons auxilia than anything else). In-universe this is most likely because if a Guardsman is going to turn to a specific Chaos god, the prospect of power and unending glorious conquest, freedom from all pain and suffering, or all the booze, drugs and whores you can handle and then some are more attractive options than being a scheming nerd. Or else Tzeentch's non-marine cultists are rarely warriors or soldiers, more often power-hungry bureaucrats, nobles, Imperial Governors, and even Inquisitors. Out of universe it's hard to make Tzeentch-focused units other than TS when their signature units are sorcerers, who only come in small quantities on the tabletop, and the Sons-specific Rubric Marines. He also offers limited knowledge of the future, represented in game with a boosted Ward save from the Mark of Tzeentch.
- Warriors of Chaos "Hero":
Vilitch the CurselingEgrimm van Horstmann. No Chaos Tribe seems to revere him to any exceptional extent (well there was this Sarl tribe and it was ruled by a Tzeentch chieftian, but Wulfrik killed him as well as his son) but he pulled out some nasty tricks such as becoming the grand magister of the Order of Light and fucking said order up before flying away on top of a dragon. Also, got Cathay in a bag.
- Sacred Number - 9
A Tzeentchian Chaos Sorcerer of the Thousand Sons Traitor Legion.
Though not as relevant as the other big four, Malal is still more notable than the other minor Gods mentioned below. He's sort of the borderline between major and minor chaos gods.
Malal is a renegade Chaos god that only appeared in one comic for Fantasy before his creators divorced and took their character with them, resulting in GW shitcanning most of the original sculptors and artists. Then he was replaced with two entirely different characters with the same basic domain before being quietly swept under the rug and forgotten, barring the odd reference that slips out here and there. He is fittingly the god of fractiousness and dissent, which means his power is parasitic: any time the four other major Milky Way Warp gods do their thing, which is to say strive to gain power at the expense of the materium and eachother, Malal grows in power as well. Because of his nature as a common enemy to the big four and thus a Warp Entity that fights the Warp, he is also sometimes a god of atheism, contradictions, and paradoxes, when he exists at all. That being said, he did have awesome champions who lived solely to hunt down the greatest champions of the other gods, which is pretty Awesome. Sadly (or not, depending on your opinion), Games Workshop idiotically lost the rights to his name, so he's been more or less retconned. Except now he might be back in 40k, with a Chaos Space Marine warband called the Sons of Malice who worship a god called Malice...who just happen to wear a color scheme of black and white, and just happen to have a symbol of a bisected skull, and whose premier Chaos weapon specializes in killing Daemons. There's also Beastmen of Malal in one of the card games. But nope, don't you dare say they worship Malal. Like Khorne, Malal has an aspect of hate, however it's more along the lines of loathing (including towards self), malice and cold contempt compared to Khorne's ragey hot-blooded variety. While a worshipper of either might shoot up a school, a malal worshipper would probably think of it like exterminating pests rather than a pleasant rampage. Beyond all that, his portfolio includes paradoxes, justice, revenge, nihilism, and the inevitability of Chaos turning upon itself. Every time the others fight or power shifts between them, he grows stronger. Just like Chaos will eventually win and consume all worlds, Malal will eventually win and consume all Chaos resulting in oblivion for all things...then if GW took the full bite off Moorcock's work and not just the parts they wanted, the whole thing starts all over again from the beginning.
- Gender - A god with a gender? Really?
- Main Enemy - EVERYONE. Because Malal's an edgy loner who doesn't play by the rules (also because he represents one of the few things GW didn't steal from Moorcock, that Chaos eventually destroys itself), although the forces of Chaos Undivided might logically be prioritized over other folk.
- Bro God(ess) - Probably any character that has been retconned away, that is angry about not being a part of the canon anymore. A story where he temporarily joins forces with someone like Emps or the C'tan might also work.
- Love Interest(s) - As per his nature as an edgelord, he has a tsundere love-hate relationship with chaos itself.
- Dedicated Chaos Space Marine Chapters - Sons of Malice. And that just about sums it up. No Imperial Guard equivalent, no daemon spawn, nothing (that we know of). So yeah, that pretty much makes him a god of hipsters too. /tg/ has made a fan-codex for Malal Daemonkin, though, so go help yourself :)
- Warriors of Chaos "Hero"/Chaos Tribe: A fellow named Kaleb Daark was Malal's first revealed servant, who swung around a pterodactyl head on a stick. The Ogre Skrag the Slaughterer fucked up dwarves in his name before pussying out to follow some shitty Ogre god thanks to retcons. There's a small tribe of Beastmen named the Claws of Malal as well.
- Sacred Number - 11
Great Horned Rat
This otherwise-unnamed deity is patron of the Skaven, and god of... well, rats. He also infringes copyright on both Nurgle's and Tzeentch's portfolios, but it's mostly rats. The Horned Rat once appeared in material form; he's the only Chaos god to do so. Of course, in Skaven fashion, he just ate a ton of the Skaven present, gave some orders and left; the Skaven only serve him out of fear, even though their belief in him only makes him stronger. He left them with a warpstone monolith containing the Skaven equivalent of the Ten Commandments.
In Age of Sigmar he was promoted to Chaos God following the demotion of Slaanesh out of the Great Game.
- Gender - Referred to as male.
- Main Enemy - Everyone, backstabbing is his primary creed and portfolio. Being cowardly, he will also work with any Chaos God, mostly Nurgle. Archaon shows him the least respect, however.
- Bro God(ess) - Nurgle, as far as his followers are concerned. They have very similar hobbies.
- Love Interest(s) - As Skaven themselves are incapable of feeling love, it is unlikely GHR can either.
- Dedicated Chaos Space Marine Chapters - None. Great Horned Rat does not exist in 40k. Although there are Death Guard miniatures with Skaven heads.
- Warriors of Chaos "Hero" - Clanrats. All of them. ALL OF THEM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Also apparently Thanquol, because the Great Horned Rat thinks his fuckups are hilarious.
- Sacred Number - 13
The Other Ones
Older editions of Warhammer Fantasy and 40k mention several lesser Chaos gods. Nowadays, they only appear(ed) in WFB (and even then, only sparingly), with some (the Horned Rat and Hashut in particular) generally considered to be separate from the "main" Chaos pantheon. Until the Horned Rat replaced Slaanesh as the Fourth Chaos god in End Times. This change did not affect 40k.
Upon completing a new set of challenges by the Chaos Gods in AoS, he was empowered to demigod level and given free reign to do whatever he desired.
The first Daemon Prince and ostensibly the only Daemon of Chaos Undivided, Be'lakor commands a great amount of power over the Realms. While still under the thumb of his four parents, he has been able to control a sizeable army of followers and has claimed to have even influenced Archaon.
The Great Gatherer
A (presumably) giant crow worshipped by tribesmen from Ulgu in the Age of Sigmar. Not much is known about him, since the only game his followers appear in isn't out yet, but we do know that the Corvus Cabal (the aforementioned tribesmen) consider Archaon to be his avatar in the Mortal Realms. Theories range from it being an aspect of Tzeentch (notable avian features, Tzeentch is known to be interested in the Realm of Shadow, maybe gathering secrets?) or Nurgle (the Crow was Nurgle's totem animal among the Norscans, maybe gathering bodies?) to being a minor, but ascending, Chaos God not so far removed from the Great Horned Rat's path to the pantheon. He even has the weird connection to both Nurgle and Tzeentch the GHR does. It has been confirmed that the Warbands from Warcry will be usable in the main game, possibly as normal units, and will have the keyword SLAVES TO DARKNESS, which means he'll have some representation in a mainline game. Not too bad for the newest kid on the block.
Hashut apparently means "Father of Darkness" in Dwarfen, which naturally means he's the god of the Chaos Dwarfs. And if his followers are any indication, he's also god of penis-compensating hats.
Mo'rcck, Phraz-Etar, and Ans'l
Puns on the last names of sci-fi and fantasy author Michael Moorcock (from whom the idea of Chaos as a fundamental force in the world was blatantly stolen/took inspiration from, and don't anyone ever say "borrow for a while" since even the author and Games Workshop have admitted it), artist Frank Frazetta (who drew a lot of movie and comic book posters, especially in sci-fi and fantasy), and Citadel Miniatures founder Bryan Ansell (who wrote several of the First Edition rulebooks). These guys helped set the tone of the early Warhammer 40,000 universe (purposefully or not), including the propensity of putting spikes on Chaos things. Games Workshop decided to pay homage in the (initial) Third Edition Codex: Chaos Space Marines, which mentioned that Chaos Space Marines often put "spiky bits" on their armour in praise of these three gods. They were never mentioned anywhere else, and probably shouldn't be considered "canonical"... not that canonicity counts for much in 40k anyway.
Originally one of the most notable Beastmen, he's worshipped as a minor Chaos God of mutation and devolution in Age of Sigmar.
Necoho is the god of atheism and one of the other minor gods invented as a replacement for Malal. Stupid as it sounds, it actually works, as Chaos is a reflection of all human beliefs and emotions, including, paradoxically, disbelief. He generally works to make religious movements disappear and wears a permanent expression of comic amusement, as he fucking knows he's a walking, talking paradox.
Note that Necoho was introduced in an adventure for Warhammer Fantasy Roleplay 1st Edition, so his current canonicity is doubtful, to say the least. That being said, he has been mentioned sporadically since then, such as the Gotrek & Felix novel Road of Skulls, which is more than can be said for Zuvassin. Has been mentioned by name in the Age of Sigmar novel Auction of Blood, along with a mention to his cult.
In the popular series If the Emperor had a Text-to-Speech Device, Magnus the Red made the point that the Emperor was, perhaps unknowingly, feeding a Chaos god of unbelief by promoting his Imperial Truth.
A joke Chaos God for Bloodbowl, Nuffle is a mispronunciation of NFL (as in "National Football League", the American gridiron football pro league in real life), which would be pronounced "Noofle" as in "book" if you tried pronouncing it. Nuffle explains why the Blood Bowl universe is so wacky and gridiron football obsessed. Technically the superior to the rest of Chaos, although apparently only in the Blood Bowl universe.
Urlf isn't a name. It's the last fucking death cry a guy makes when you gut him. That should tell you all you need to know. Anyway, this guy used to be a Norscan (like most of the daemon princes on this list) and was elevated to princehood by Khorne for exceptional badassery. Before his ascension, he was a massive, tall, bearded, Clint Eastwood-type Chaos Champion and was a chieftain of the Snaegr clan of Aeslingr. He's so fucking powerful that he was able to create his own lesser daemons and can bless warriors with the Mark and mutations of Khorne. Urlf has his own summoning days like most powerful daemon princes, and is usually worshiped as a lesser deity of Chaos by those who serve his master, Khorne. He has a short story in the 6th edition Chaos army book, where he muses on the fuck-you nature of time in the Warp and remarks on how the new Chieftain of the Snaegr resembles one of the sons he fathered in his mortal life. He also blesses the new chief with Khorne's mark and turns him into a monstrous cross between a Bloodletter and a Chaos Champion.
Zuvassin is one of the two minor gods invented as a replacement for Malal. He just likes to see shit fall apart, specifically nonphysical stuff like schemes and lives - in other words, he's the god of not as planned. He's the guy who makes all the bad shit happen in infomercials. Generally, he makes sure that Murphy's Law is always enforced in the most spectacular possible ways. He doesn't have many worshippers, as he makes sure to fuck up whatever they're planning too.
Note that Zuvassin was only introduced in an adventure for Warhammer Fantasy Roleplay 1st Edition, so his current canonicity is doubtful, to say the least.
Actually, he is still canon, at least in Warhammer Fantasy. The 2nd Edition "Tome of Salvation" actually lists both him and Necoho as Chaos Gods.
When Tzeentch was the best
According to recent Tzeentch Codex/Battletome Tzeentch was at one point the sole major chaos god. A rebellion against him fractured him into many pieces, which because of warp time fuckery, technically counts as a different god. When chaos was first forming (just after War in Heaven for 40k) there were many chaos gods and entities competing (rather than the total domination that exists now). Tzeentch somehow became number one, and was a super god of sorts, although he was possibly less powerful than the current Tzeentch due to the lesser size and influence of chaos. A rebellion by all the other chaos gods fractured him, creating the Tzeentch we know today. In the same way that Slaanesh has always existed in 40k, the new Tzeentch has always existed the way he is. While the old Tzeentch is permanently destroyed (across all time), while still doing the things he did. They are implied to be two seperate entites.
This is a variant of the backstory of The Blue Scribes.
|The Chaos Gods of Warhammer 40,000 and Warhammer Fantasy|
|Four Main Chaos Gods:||Khorne - Nurgle - Slaanesh - Tzeentch|
|Other Gods of Chaos:|| Archaon - Hashut - Horned Rat - Nuffle |
Malal - Necoho - Zuvassin
|Chaos Gods of Law:||Alluminas - Arianka - Solkan the Avenger|