Sealed Army in a Can

Hmm, what's this? Want to Take Over the World? Cause mayhem? Have you considered the Sealed Army in a Can? Guaranteed to provide decades of destructive entertainment, try it today!

The Sealed Army in a Can is an army that was so powerful that it was impossible to destroy them and the best that could be hoped for was sealing them away, usually at great cost. With works that employ this trope you can invariably expect that the Big Bad's master plan will revolve around awakening this army to do his bidding whether it be to Take Over the World or just break things. Often times you will get the Sealed Evil in a Can thrown in with them as a nice bonus. Like the Sealed Evil in a Can the fact that they were sealed away may have weakened them to the point they can be destroyed or technology has advanced to the point where it can get the job done. Or not.

Unlike a real army that is composed of individuals, the sealed in a can variety don't seem to have any sentience and will often mindlessly follow whoever freed them.

Can sometimes be used as Sealed Good in a Can for a really Big Damn Heroes moment. In these cases they may not be quite as mindless. For several unique characters (often in seperate "cans") see Sealed Cast in a Multipack.

Sub-trope of Badass Army except more so (otherwise, what's the big problem?).

Anime and Manga

 * Hellsing: Alucard has the ability to summon people he's drained as familiars. Towards the end, he summons everybody he's ever eaten, ever
 * Capone "Gang" Bege of One Piece has this as his power, where he seals an entire army in himself. This allows him to brazenly stroll into a battlefield alone and still wind up with superior military force once he ejects them.
 * There also is an example in the Naruto Manga where it's revealed that Zetsu, given a sufficient amount of chakra can spawn an army of 100.000 clones of himself.

Comic Books

 * In ROM Spaceknight, Rom's preferred weapon, The Neutralizer, banishes his enemies into Limbo. Thus some Dire Wraiths stole the gun, and later captured Rom, in the hopes of finding a means of returning the many Dire Wraiths he banished and thus create an big renewal of their forces.

Film

 * The Lord of the Rings: In a variation on this trope Aragorn gains control of one of these in both the film and the book The Return of the King . Different from most examples in that they retained their sapience.
 * The Mummy Trilogy:
 * In the second movie the mummy returns and attempts to gain control of the Army of Anubis. They can only be sealed away, not destroyed.
 * The Dragon Emperor's Army in the third movie,
 * The Golden Army from Hellboy II. An army of 4900 (More accurately, 70 times 70 soldiers) invincible, untireable, clockwork warriors, to be precise. They're controlled by a MacGuffin that was split into three pieces to prevent it from ever being used again.
 * The buried alien army in The War of the Worlds remake.
 * The Mahou Sentai Magiranger movie has an evil army that would be unleashed if Groom no Bridon marries someone pure and good, so he kidnaps the red ranger's Love Interest.
 * Babes in Toyland (a/k/a March of the Wooden Soldiers) features an army of toy wooden soldiers that were built outside specification (100 wooden soldiers each six feet tall, instead of 600 wooden soldiers each one foot tall). They come in handy defending Toyland from the boogeymen.

Literature

 * One of these were found under the Long Man in Lords and Ladies. They're supposed to wake up in time for some final battle when a wolf eats the sun.
 * Interesting Times has Rincewind discover the "real" Red Army, and use it to save the revolutionaries.
 * In Making Money, the four Gold Golems comprise one of these.
 * In Fate/Zero, Alexander the Great, A.K.A. Iskander, can summon a regiment of his former army at will as his Noble Phantasm. They all manifest as lesser Heroic Spirits, and some of them are genuine Heroic Spirits as well.
 * In The Dragon in the Sword, by Michael Moorcock, the Eternal champion manages to get access to one of these, composed of all the heroes throughout eternity that fell. (It's implied that they're ones who tried to stop fighting). Each one is described as being as skilled as Erekose, who is able to take on 6 mooks without too much trouble. They take on the concentrated might of all of Chaos.
 * The Horn of Valere from The Wheel of Time. Whoever blows it can summon the Heroes of the Ages to fight for him. Of course, everyone wants it.
 * In Robert Heinlein's The Door Into Summer he mentions in passing that the USA was able to win a war against Russia because of reserve troops kept in suspended animation.

Live Action TV

 * Buffy the Vampire Slayer: seen in season 7 when Buffy & co. have to fight.
 * Angel: A subversion is used where Eldritch Abomination Illyria attempts to conquer the world by raising her invincible demon army that has waited underground while she was sealed away dead. However, it has since crumbled to dust due to the passage of time.
 * Used a number of times on Doctor Who.
 * The Cybermen in "The Tomb of the Cybermen"
 * Daleks in both "Planet of the Daleks" and "Doomsday". ("Doomsday" also has Sealed Evil in a Can in the form of the Cult of Skaro, an elite group of special Daleks who release the army, in an unusually literal application of this trope. The entirety of the army is sealed in a metal can the size of a single Dalek. It used TARDIS tech.)
 * Kane's mercenaries in "Dragonfire"
 * Played with an interesting twist in Power Rangers Ninja Storm. In the finale, it turns out that, unbeknownst to either the audience or the Rangers, the heroes haven't been killing the monsters of the week, they've been sealing them. And the Big Bad was keeping track of the exact number of monsters the can could hold, as when it went one over, it would let them all out at once.
 * Interestingly enough, the Beetleborgs did the same thing, since the Monster of the Week was always summoned out of a comic book, and "returned to the printed page" at the end of the episode. The season finale featured newly-created Villain Sue Nukus suggesting they summon them all again, this time all at once.
 * Power Rangers Operation Overdrive The Fearcat army in a magic mirror.
 * At any given time the majority of the Wraith are in hibernation, as the human populations they feed on couldn't support all of them at once. However, when those currently awake find out about the 6 billion humans available on Earth they begin waking the rest up.
 * The Season 2 finale of Supernatural has an agent of the show's Big Bad

Mythology

 * Jason was given the task to sow a field with dragon's teeth, which sprouted into a huge, invincible army. However, he defeated them by . There's probably a message in that somewhere.
 * The Myrmidons in The Iliad were ants who would turn into warriors and provide Achilles with an invincible army.

Radio

 * The Mariage in StrikerS Sound Stage X of Magical Girl Lyrical Nanoha. Discovered during an archaeological dig. Beaten due to their Necromancer king having an anti-war point of view by that time and therefore not being too privy about sustaining their diminishing numbers.

Tabletop Games

 * The Necrons from Warhammer 40,000 are a variation in that they can't be controlled and their only goal is to eradicate all life from the universe. Additionally, unlike most sealed armies they can wake up anytime they want and will voluntarily seal themselves away for centuries at a time to wait for victims to make themselves available.
 * Dungeons & Dragons adventure OA6 Ronin Challenge. Underneath the city of Tempat Larang is an army of 500,000 infantry.

Video Games

 * The Spirit Army from Mortal Kombat. Resurrecting it was the villains' plot for Deadly Alliance, and it was completely and totally destroyed in the opening of the following installment, Deception.
 * The Chimera from Resistance are a bit of a variation in that they aren't sealed away, the means by which they get more soldiers is.
 * In Loom, the Archbishop Mandible has a grand plan to release an army of . This turned out to be not such a great idea.
 * The Terracotta Army is available as a wonder in Rise of Nations, that grants a bonus of troops (unsealing a platoon?) after a while in the game during the campaign in another territory, and generates one light/modern infantry at regular intervals based on the number of existing infantry when present in a match.
 * The second to last scenario of Command & Conquer 3: Kane's Wrath involves activating an army of cyborgs Kane has hidden away, and the last mission involves using said cyborgs to storm a massive GDI Complex.
 * The Darkspawn from Dragon Age are another example as they show up every few years and just start killing their way through the kingdom.  In the meantime they just stay in the Deep Roads fighting the dwarves and rarely going to the surface.
 * The Myrkridia, a terrifying race of Exclusively Evil humanoid monsters in the universe of Myth and its sequels, were sealed in a small artifact call the Tain. Various plotlines involved Myrkridia getting out of and/or the protagonists (and their armies) being trapped in it.
 * Prince of Persia has an entire Sealed Army in a Can in The Forgotten Sands.
 * It's heavily implied that this happens to the Iron Legion of Xylvania in Battalion Wars when the Solar Empire uses its super weapon to defeat them.
 * Confirmed in the last leg of the game in which
 * hidden in Fortification Hill in Fallout: New Vegas, the door to which can only be opened by the thing you were mugged for at the start of the game.
 * The Minion Hives in Overlord 1 & 2 have to be recovered to grant the Overlord a replenishing supply of various forces.

Western Animation

 * While it's only described in detail on the film's accompanying website and in the artbook, the Warriors of Tenshu from Kung Fu Panda practically scream to be used in this fashion as a Badass Army for the heroes. Here's hoping the repaired Urn of Whispering Warriors does show up in a sequel...
 * The Cauldron-Born from The Black Cauldron and the original story.
 * In Conan the Adventurer, most of the Serpentmen are still sealed in the Abyss along with their demon-god Set. The heroes' Starmetal weapons can send the remaining Serpentmen to Set's side in the Abyss as well.

Real Life

 * The Terracotta Warriors are, according to legend, one of these.
 * The page picture is of a sculpture garden by Antony Gormley, who has this motif among his themes. He's also made a garden of wood and cement blocks shaped like real people (he took their measurements).
 * Neo-Nazi movements, and extremist movements in general are the closest real life examples known.
 * The Russian Navy is this, sealed away by its lack of any ports that don't freeze over except on the Black Sea where it is bottled up by Istanbul controlling the mouth. As a result several naval powers have had sort of a standing This Means War on any attempt by Russia to conquer Istanbul, going back several generations.