Just about every modern sci-fi setting has a military that uses Drop Pods to deploy; if you take a sufficiently broad interpretation, you could say that the Martian cylinders from H. G. Wells' The War of the Worlds were the very first drop pods, but it was Robert Heinlein's Starship Troopers that really crystallized the concept as we know it: a means of deployment for super-elite soldiers right where they are needed, when they are needed, and in style.
The Deep Strike is the Space Marine's iconic deployment method. A pod holds ten Marines, one Dreadnought, or one Thunderfire cannon with gunner. It takes a lot of the guesswork out of Deep Striking because it avoids obstacles automatically -- that's why Boreale loves them so much. For entirely unexplained reasons, once the pod lands, no one can stand (or sit) inside it again - everyone has to get out, and then some sort of miracle bars them from re-entry.
Adeptus Astartes Drop Pod
The classic and original STEEL REHN! The drop pod is capable of carrying up to 12 Space Marines into combat. They are launched from a vessel in low orbit towards the drop zone, usually in the midst of or near a battlefield. Once launched, the Drop Pod plummets through the atmosphere until its retro rockets fire to slow its descent. Although certain overly zealous marine chapters are known to use their drop pods as giant orbital bombs; dropping the drop pod at full speed until it eventually crushes any unfortunate heretical bitches underneath and indirectly/directly killing their occupants from sheer impact. A Machine Spirit (on-board computer) guides the Drop Pod to its destination and can receive further commands from the Pod's mothership.
Like most drop pods, they become immobile and pointless once they land, with the only use they have post-crash is to act as some sort of limited cover for the marines and fire support from its internally built weapon turrets (Usually in the form of a single Storm Bolter or Deathwind Missile Launcher). However, it can later be recovered by the Chapter's Techmarines and reused if it is not destroyed.
When a Drop Pod is modified to carry Space Marines in Terminator Armour, two standard-sized restraints must be replaced with a single large restraint due to the sheer bulk of Terminator Armour.
Certain versions of Drop Pods such as the Dominica Pattern Drop Pod used by the Sisters of Battle and inquisitorial strike forces, last seen in 2002, only holds five people, the rest of the space probably being used with shock dampeners to make up for the occupants' lack of superhuman physiology, or a votive shrine.
Additionally, the assassins of the Eversor Temple are deployed in special Drop Pods that prepare them for their missions. These Pods are equipped with neuro-links that feed the details of the mission to the assassin while remote links activate and begin to prepare his body for the task at hand.
Deathstorm Drop Pod
A drop pod that holds weapons instead of soldiers. Ergo, the ultimate Trap Drop Pod bristling with Just As Planned. If a drop zone is just too hot to land in, the Space Marines will use Deathstorm Drop Pods (equipped with assault cannons or Whirlwind missile launchers) to clear the way. They're only BS 2, but they compensate through volume of fire (they fire D3 times at every unit with 12" the turn they come in).
Deathstorm Drop Pods were first conceived and prototyped by the Raven Guard Legion during the Great Crusade, who sought to augment the firepower of their precision-orbital assaults. The Raven Guard's preference for such surgical-strike tactics would, upon occasion, leave them at a disadvantage in the case of both protracted engagements and in assaulting very heavily fortified targets where heavy units such as Legion tanks and artillery could not be used. So they compensated by loading a bunch of heavy weapons on each end of the Drop Pod's door and voila! The Deathstorm was born!
It would be a heartening sight if the Navy were to use these en-mass to support the Guard. Come to think of it, a massive volley of these things would be highly effective against Orks, Tyranids, and possibly Necrons. They could also be useful as a rapid, highly potent response to daemons. After all, the fluff says fighting daemonic hosts is very difficult because they can poof anywhere on the battlefield, so there are no real battle-lines in such an engagement. In that vein, they may be useful against Eldar of all types, too. Hell, just shoot huge numbers of them at anything that looks at you wrong.
Its predecessor, the Deathwind Drop Pod is no longer used by the Adeptus Astartes. This variant, similar in nearly every way to the Deathstorm variant that ultimately replaced it, was originally armed with Deathwind Missile Launchers to provide fire support. This variant has been replaced with the Deathstorm variant due to Whirlwind Missile Launchers being more powerful than Deathwind Missile Launchers and just as easy and cost effective to manufacture. But not launched from a drop pod and therefore we can assume either the Deathwind is secretly used or, more likely, they just slapped Whirlwind Missile Launchers on and called it "Deathstorm" and hoped the AdMech didn't notice.
Dreadclaw Assault Pod
The only drop pod that could actually be reused.
The Dreadclaw was one of the most advanced if not the most advanced drop pod that the Imperials actually got a hold on. The fact that it could fly back up to its mothership and still be able to be 'resupplied' with even more marines without being limited to the amount of drop pods you can use, makes the Dreadclaw absolutely Awesome....if you ignore the fact that the Dreadclaw is also the most notorious drop pod, notable in turning its occupants into mincemeat, not so Awesome.
The Imperium used to use the Dreadclaw, until they learned that its design made it receptive to the influence of Chaos during the Horus Heresy. This was not a problem for Chaos Space Marines, who use them to this day. Unfortunately, they are both more versatile and more deadly than drop pods; capable of being used as assault boats or drop pods and then return to orbit to get more marines. They also have plasma cannons to blast everyone with.
Its machine spirit had been described as being unusually blood thirsty, which often caused lethal "incidents" with maintenance crews, and even Marines themselves, even before the pods fell to Chaos, hence why the Dreadclaw wasn't very popular amongst legions, who actually gave a fuck about their mortal serfs. And then when the Heresy kicked off and the Dreadclaws began actively sabotaging ships, the last thing Imperial Navy captains wanted was a bunch of murderous pods with heavy Melta guns right next to their bulkheads.
That said, for the Chaos Legions, they've become much more safe and docile.
Also, somehow, evidence suggests it's daemon proof. When daemons are too scared or can't even possess them, you know it's good.
Lucius Pattern Dreadnought Drop Pod
A drop pod with all the restraints and harnesses taken out, and only three fins instead of five. The Lucius was a obviously much larger variant than the standard Drop Pods of the Legiones Astartes and had a more powerful engine to compensate, allowing for a dangerously meteoric descent to the battlefield. This means that only a Dreadnought can survive landing in it.
This Drop Pod pattern is the largest known Drop Pod variant used by the Adeptus Astartes save for arguably the Kharybdis Assault Claw, and is capable of delivering a single Dreadnought into combat.
The Dreadnought Drop Pod uses three or four large external door ramps as opposed to the smaller ones used on other types of Drop Pods. These Drop Pods are capable of delivering both Contemptor Dreadnoughts and now-standard Castraferrum Pattern Mars Mark IV and Mark V Dreadnoughts to the battlefield.
Previously, it allowed it to assault as soon as it landed, but now, when nothing can assault from reserves Lucius DP have been changed to granting Shrouded for himself, and everything hiding behind it or on it on the turn it deep strikes, likely to represent cloud of dust, dirt and debris, raised by its meteoric descent. Oh, and the dread can stay inside the pod, to use it as ablative hull points, and even fire his weapons from the inside, as it's open-topped. All in all a great way to deep strike your dread, and be sure he won't be shot off board the turn it drops.
Found in IA2:2nd, these pods also have drop pod assault and can get precision deep strike for 20pts using Dropsite Massacre legacy rules in the appendix, but as drop pods they already had the ability to reduce scatter. Yes it still has the assault vehicle rule (despite already having it for being open toped - typical Forge World rules stupidity for you), but that still doesn't actually allow things to charge the turn they deep strike, very few things get around the BRB that way.
Kharybdis Assault Claw
A Super Heavy Drop Pod used during the Great Crusade, capable of carrying twenty Marines or a pair of Dreadnoughts. Also used for burning shit with its engines as it flies over it, and melting shit it lands on (not to mention having the ability to fly back to its ship for another batch of soldiers to make planetfall). Sadly, the Kharybdis suffered similar problems as its smaller brother, the Dreadclaw. While the latter had a malevolent AI that caused lethal "accidents" (which became much more frequent when the Horus Heresy started and which forced Imperial Commanders to simply jettison them into the blackness of space), the Kharybdis (while also having an AI) had it differently.
The AI of the Drop Pod tended to bond with a person and became violently unpredictable whenever its preferred handler wasn't around. If the handler somehow died or became unable to tend to it, then the bonded Kharybdis had to be jettisoned or destroyed since it would refuse to allow anyone else inside its hold- and tended to demonstrate this by opening its doors in mid-drop to incinerate anyone riding in it. Thus no Space Marine Chapter has a single one these days, though Chaos Marine Legions still have some in their armouries.
Because of its ability to essentially punch through meters thick armor like butter, they are also popular as makeshift boarding vehicles in the Imperial Navy. The arrival of a flight of these ominous Assault craft, boarding hooks extended as they approached their target, signaled that asses are going to be creamed whoever that dared opposed the Legiones Astartes.
Some unorthodox commanders who have watched one too many Mad Max movies or grew up on a Ork infested world; thereby prompting these individuals to employ the Kharybdis as a tank hunter, ramming enemy armor in low-altitude attack runs. It is basically the marines' equivalent of the Tyrannocyte. This also demonstrates how maneuverable drop pods and their various types are and how insanely tough Astartes are.
Each member of the Mobile Infantry gets his own pod, containing his suit of armor. The armor is actually perfectly capable of surviving re-entry, and can even fly ("a little," as Heinlein writes); the pod is actually meant to disintegrate in the atmosphere, giving the Mobile Infantryman a cloud of chaff to confuse ground defences. About five empty pods designed as pure chaff are also deployed for each occupied one for additional protection.
In the Command & Conquer universe, by the era of Tiberian Sun, GDI makes use of drop pods, fired from their orbital space station Philadelphia as very quick response troops. The pods are rather small, holding only one trooper each, and have forward mounted machine guns which give off a nice hail of gunfire while dropping to at least somewhat clear the landing zone. While the soldiers come as Elite ranked, they are only otherwise regular Light Troopers and Disc Throwers (though the first mission's FMV depicts them having some kind of crazy Railgun/beam weapon). Was only available when mission triggers dropped them, but as of Firestorm, the Upgrade Center gave you the choice of building a plugin for a rechargeable targeted power, fuck yeah.
By the time of the 3rd Tiberium War , GDI is capable of dropping 3 squads worth of Zone Troopers, elite, jumpjet and heavy power armour equipped infantry specialized in operating in tiberium infested areas who use fucking railguns to shit fury down Nod's alien radioactive crystal loving throat and punch its tank divisions in the dick.
The UNSC, Covenant, and Banished are known to use utilize drop pods. The UNSC uses the S.O.E.I.V.(Single Occupant Exoatmospheric Insertion Vehicle) to deploy Spartans and more commonly ODSTs. The pods are fitted with a viewport, several screens to monitor their squadmate's descent, and a rack to holster several weapons. The covenant and banished use several types of pods that can contain 1 troop up with only the ground to slow their descent, to several that are designed with rockets to slow descent and energy shielding for the personnel.
A Jokaero Drop Pod.