Many Spirits Inside of One

My name is Legion, for we are many.

—Mark 5:9

My name is Legion
For we are many spirits

Inside of one.

—Hammerfall, "Legion"

Some people are victims of Demonic Possession or Grand Theft Me. Others suffer from Split Personality, or even outright Super-Powered Evil Side, and have to struggle with Enemy Within. All those things are terrible in their own way, but don't worry, they can always be even worse. It's one thing when your body is taken by the lord of all evil himself, but when he invites his twelve best drinking buddies to join the ride, that's something else entirely.

This trope is what you get if you take Demonic Possession or Split Personality Up to Eleven. Instead of having one evil being taking over somebody, it's multiple evil beings. Somebody doesn't have just Jekyll and Hyde inside his head — it's Jekyll, Hyde, Steve and Edmund. And Zoidberg.

The Trope Namer is a song by Hammerfall, based on the famous biblical tale of Legion, man possessed by multiple demons, which is obviously the Trope Codifier. Contrast I Am Legion, another trope named after this tale, which occurs when members of a group start referring to themselves as a group, rather than individual people, implying that they lost their individuality.

Compare Mind Hive, a similar trope which occurs when multiple minds are trapped in one body, but are neither demons possessing it nor split personalities.

Examples of Many Spirits Inside of One include:

Anime & Manga

• Battle B-daman has Bull, a boy with three personalities: calm one, confident one and aggressive one.
• Although for the most part, she actually only has one personality (the other one almost never comes up), in one Sayonara, Zetsubou-sensei chapter, this is done with Kaere. She's the Fauxreigner Foreign Fanservice character and she splits into an entire United Nations' worth of personalities.
• In Bleach Ichigo Kurosaki shares his body with the spirit of his weapon, Zangetsu, and his Super-Powered Evil Side, Hollow Ichigo. Zangetsu and Hichigo seem to be representations of his powers, rather than his psyche, but still.
• Shinobu Sensui from Yu Yu Hakusho has seven personalities.

Comic Books

• In X-Men Charles Xavier's son, Legion, once had multiple personalities with different superpowers. Then he went better, but as a whole was so powerful that he caused the Age of Apocalypse. He later came back, now having hundreds of personalities, each with its own unique power. Some of them are minds of dead people he drained, making him a combination of this trope and Mind Hive.
• The Incredible Hulk: At the beginning it was only Bruce Banner and the ruthless Gray Hulk, who turned green and then started getting constantly dumber until we get the most well-known version of the character, the Savage Hulk. Later a new Gray Hulk, a mischievous and selfish version of the first gray Hulk, joined them. Then the Hulks and Banner merged into Professor Hulk, who was later retconned to be a completely different personality altogether. Recently, the four of them have been joined by Green Scar — an intelligent, brutal warrior persona. There was a story revealing that Banner has a lot more Hulks in his mind, including such creatures as the lizard-like Guilt Hulk or the monstrous Devil Hulk, but the question of whether it's still in the continuity remains debatable.
• Jill Presto from Lucifer is host to 12 Basanos.

Film-Live Action

• In The Exorcism of Emily Rose Emily at one point starts speaking in demon voices as the demons say there are many of them in her and each one has possessed a different evil person throughout the history. Movie is Very Loosely Based on a True Story of Anneliese Michel, who was suffering from severe mental problems and had many seizures. She also believed she was possessed, specifically by Lucifer and several evil people throughout history, including Cain and Adolf Hitler.

Literature

• Matthew Swift shares his mind with the numerous entities known as The Electric Blue Angels to the point that the first person narration is constantly switching between "I" and "We"
• The novel John Dies at the End, by Cracked.com's David Wong, gives us Shitload, who is the host body of a hive mind.
• At the end of Children of Dune, Alia is overcome with the personalities of the past lives within her and starts speaking with many voices.
• In the Discworld books there's Altogether Andrews, a man with about eight personalities, of whom none are named Andrews. It's theorized that he was a medium who was too accommodating to lost spirits, and ended up getting pushed out of his body.
  • There's also Tiffany Aching in A Hat Full of Sky who is possessed by a Hiver.
  • Subverted in Myria Le Jean. The Auditors possessing her named this body expecting continued collectivism, but the form bestowed individuality upon whatever Auditor force(s) operated it, and at the end she changes her name to Unity.
• Shades from the Inheritance Cycle are sorcerers whose bodies have been taken over by the spirits they command. The first one we meet (Durza) only has three spirits controlling him, but in the third book, we meet one who has twelve.
• It's indicated this may be the case with Randall Flagg in The Stand. After Tom is put into his trance, he talks of the New Testament references-Flagg's name being Legion and Jesus driving him into a herd of pigs once.

Live Action TV

• In a Stargate SG-1 episode, Doctor Jackson has been possessed by personalities of multiple members of a spaceship's crew. Surprisingly, it was one of the rare examples when possession in this show wasn't evil.
• Star Trek: The Next Generation episode Masks: Data is possessed by an alien probe, and takes on the personalities of various figures from the mythology of an extinct civilization. Mainly an excuse to let Brent Spiner act his nuts off.
• In the Star Trek Verse, the Kurlan believed that a person was made up of a group of individuals, each with his own voice. A Naiskos was a sculpture representing a person, which could be opened to reveal several little people inside it.
• Alpha and Echo on Dollhouse, who don't forget their previous implants.
• In Kamen Rider Den-O, the main Rider is possessed by an Imagin. ...then another, and another. When suited, each possessor makes a different Den-O with a different Weapon of Choice. Though they're not all in him at once, any can take over at will. Hilarity Ensues (literal, non-ironic hilarity, that is) often.
  • When he uses Climax Form, Momotaros seems to remain the "default", but the other spirits are represented by pieces of armour. They can and do start arguing over how to go about things.

Religion

• There's another New Testament reference — St. Matthew XII, xliii.–xlv.:

And when an unclean spirit is gone out of a man he walketh through dry places seeking rest, and findeth none. Then he saith: I will return into my house from whence I came out. And coming he findeth it empty, swept, and garnished. Then he goeth, and taketh with him seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is made worse than the first.

• • Of the little the Bible says for sure of Mary Magdalene, one thing is that Jesus drove seven demons out of her.
• Possession by multiple spirits is a core element in Korean shamanism, which is claimed to be a close descendant from Siberian shamanism, arguably the first religion of Homo sapiens. In a ritual, the shamans invoke multiple spirits to possess them one after another, so that they can borrow multiple powers to accomplish a goal. Somewhat frightening to see in real life.

Video Games

• Portal 2 reveals this of GlaDOS. From whom in the first game, you remove and destroy personality cores.
• One of the DLC characters for BlazBlue is a Magical Girl with a rather unpleasant female personality, a nicer male personality and one of the six heroes sharing the same body.
• The Mask of the Betrayer expansion pack for Neverwinter Nights 2 gave us One-of-Many - an amalgamation of several hundred spirits. He is governed by the worst of these - and as a result he is a twisted monster that keeps tempting you to do evil and add additional spirits to "the many".
• Legion from Mass Effect is a single body inhabited by numerous operating systems. Despite seeming very similar, they were split evenly when you must decide whether to kill or convert the Geth heretics.
• Ermac from Mortal Kombat is this, especially later in the series.
• In Live a Live, O. Dio from the Western Chapter. He's actually a horse possessed by the vengeful spirits of a regiment that got wiped out, taking out their hatred for humanity on an old west town. The horse returns to being a horse after O. Dio is defeated.
• Sora from Kingdom Hearts habitually invites other people in, although he usually isn't consciously aware of doing so. At this point he's renting out space to Ventus, Xion, Roxas, and probably Vanitas, and Kairi was also in there for most of the first game. Most of his tenants are fairly nice people, but all but two of 'em were trying to kill or suppress him at one point or another, intentionally or not.
  • The villain of the series, Xehanort, is this as well, notable in that, for most of the series, he's the hijacker, with the proper owner body being Terra. It counts as this trope because Terra took in Master Eraqus as a passenger shortly before Xehanort did his thing.
• In Umineko no Naku Koro ni, by the end of the series, you can count at least three and possibly four different personas that are within Shannon's body. Besides her, there's also Kanon and Beatrice, who is kinda also Yasu. However, if you count all of her imaginary friends who don't actually take control of her body, the number of people in there easily jumps into the double-digits. It's a stinking party in her head.
• In the Playstation 2 title Guilty Gear XX there's Zappa; A polite and friendly Aussie who's perfectly normal on the surface (Save an eccentric taste in wardrobe) except for the fact that he's the unknowing host to a grab bag of crazy ghosts including a spectral sword, a few dozen wisps, a hellhound, and an armor-clad lightning spirit. The most powerful and malevolent of his "guests" is S-Ko who readily takes control of him whenever he attempts to interact with other people. Unlike S-Ko, the weaker spirits are loyal to Zappa, often comforting him whenever he is depressed or sad.
• ExDeath from Final Fantasy V is a living tree with many evil spirits sealed inside him. The release of these spirits combined with the power of the Void are what cause him to transform into Neo ExDeath at the games' end.
• Turel from Legacy of Kain is possessed by several hundred hylden ghosts when you find him in defiance, they later move on to Raziel as part of their Xanatos Gambit to inspire him to go through with killing Kain.

Web Comics

• Tina from Wapsi Square is a "rats running the ship" version of this. The original Tina died long before the comic started, and her personal demons decided to take control of the body and walk out of the morgue. And what did these demons living on their own do? They opened a coffee shop.

Western Animation

• Blitzwing from Transformers Animated has three personalities - a cool, calm tactician with ice blasts, or more awesomely, ice missiles; a rowdy, battle-loving hothead with fire blasts; and a cackling, non-sequitur spouting Talkative Loon who can use either of their powers. He's also got two vehicle modes: Icy uses jet, Hothead uses tank, Random uses either.
• In one episode of Batman: The Animated Series, Two-Face developed a third persona: Judge, a ruthless vigilante who was punishing criminals. Both the Harvey Dent and Two-Face personas were unaware of Judge's existence. It also seems that Judge didn't know he shared a body with them, since he was ruining Two-Face's plans and tried to kill him.
• In Avatar: The Last Airbender, the titular Avatar is normally just one person with the ability to use all four elements. If that person accesses the Avatar State, usually through an Unstoppable Rage, he contacts the spirits of every single Avatar before, channeling thousands of spirits through one mortal body. It's a little bit scary.

Real Life

• A milder version (which may have been flanderized to this trope) is when people have inner conflicts and don't know what they should do. Like Faust by Johann Wolfgang von Goethe said: "Two souls alas! dwell in my breast."
• Modern neuroscience backs this up. As an experimental treatment for severe epilepsy, some people have had their corpus callosum severed, to prevent seizures from swamping the entire brain. This leaves the two halves of the brain, left and right, intact but unable to "talk" to each other. Result: the patients exhibit some fascinating behaviors that almost seem to indicate two different people living in their heads! (It is, however, limited to two.) The implication is that we all have two people in our heads, but they work in such close tandem that we rarely notice...