The Unversed (アンヴァース Anvāsu?)[1], meaning "those who were not well-versed in their own existences", are the main enemies of the game Kingdom Hearts Birth by Sleep. They are considered "the opposite of human life" and grow from the negative emotions produced when Vanitas was created from Ventus. It is because of this that Vanitas is able to control them. By all accounts, the Unversed are extensions of Vanitas himself, and part of his power and influence—effectively making him the first and original Unversed.

Chronologically, the Unversed are either the first or second enemy referenced during Deep Dive, as they are the second race to manifest, but the first to attack the Realm of Light.

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Vanitas is an Unversed and one of the primary antagonists in Kingdom Hearts Birth by Sleep. He is the apprentice of Master Xehanort. Created by Master Xehanort, Vanitas is the embodiment of the extracted darkness from Ventus's heart. Vanitas's birth sparked the threat of the rest of the Unversed."Good. Let's see what you're made of."
—Vanitas to Ventus before their first battle

Hades is a villain from the Kingdom Hearts series, originally from the 1997 Disney animated feature Hercules. Hot-headed literally and emotionally, he will stop at nothing to see the end of Hercules.When Maleficent began her conquest of the worlds, Hades became one of her allies. He utilized the Heartless by supplying them as monsters to the Olympus Coliseum, for heroes to battle as usual. However, he also gained the assistance of Cloud Strife by making a deal: if Cloud kills Hercules, Hades will lead him to Sephiroth (who he apparently does know the location of, as Sephiroth is indeed at the Coliseum). Hades additionally provided Sora with a pass to enter the Coliseum games. When Sora appeared to be winning in the Coliseum however, Hades instructed Cloud to kill Sora as well. When the plan failed (either with Cloud refusing to deal the final blow to Sora, or with Sora defeating Cloud; it depends on the result of the battle), Hades had Cerberus attack Cloud. However, Hercules rescued Cloud and Sora defeated Cerberus.

As Sora left the Coliseum, Maleficent warned Hades not to be overcome by the darkness. Hades sent Maleficent away, claiming he could handle it. He ironically was not overcome at all (while the rest of Maleficent's followers and Maleficent herself ended up being overcome, with the other exception of Captain Hook). Strangely, Maleficent overlooked the fact that Hades was the immortal god of the dark underworld. This lead to the inevitable irony of Hades outliving Maleficent as well as being currently the only villain in the whole series to show up in all the games and survive and will probably continue to survive due to him being a god.

When Hades learned of Maleficent's demise, he took matters into his own hands. Hades, determined on personally defeating both Hercules and Sora, opened the Hades Cup in the Coliseum. The long, grueling tournament had a battle with him near the end. Unfortunately for Hades, Sora defeated him in the battle, knocking him into a cell where he was beaten up by someone. After a few more battles in the cup, though, Hades decided on a way for revenge.

In events very much like those in Hercules, Hades unleashed the four Titans upon the world (although only two are seen, it can be guessed that the other two and possibly the Cyclops were as well). When Sora reached the final rank in the tournament, he had to combat the Rock Titan. Upon its defeat, Hades apparently went into hiding.

"Did you forget who you're talking to? I am the Lord of the Dead!"
—Hades

Hercules is one of the primary characters featured in the Kingdom Hearts series. He is a demi-god and son of Zeus, living on Olympus Coliseum. His enemy is Hades, lord of the Underworld. Hercules possesses great strength and can battle the toughest of monsters. He is very supportive of Sora's goal to become a true hero.

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Tinker Bell is the little fairy who lives in Neverland alongside her best-friend, Peter Pan and has appeared in Kingdom Hearts, Kingdom Hearts: Chain of Memories, Kingdom Hearts II, Kingdom Hearts 358/2 Days, and Kingdom Hearts Birth by Sleep. She is originally from Disney's Peter Pan.Tinker Bell is introduced to Sora, Donald, and Goofy when they meet Peter Pan in the hold of Captain Hook's galleon. Tinker Bell informs Peter that she has located Wendy (she, however, has a deep jealousy for Wendy, due to her growing relationship with Peter). Tinker Bell later sprinkles the trio with her pixie dust for later use of flight. Peter rescues Wendy and flies off somewhere, leaving Tinker Bell and the others to fight for themselves.

Tinker Bell is then captured by Hook and held hostage in a lantern - her life or the Keyblade is Hook's demand. Sora walks the plank instead and flies thanks to happy thoughts. Peter returns and saves Tinker Bell from Smee. After Captain Hook takes the plunge and is defeated, Tinker Bell reappears and tells Peter of something happening at the clock tower in London. They go to the clock tower (Big Ben) in London where Sora seals the Keyhole. Tinker Bell seems to approve of Peter and Wendy's friendship at last and Peter asks Sora to take Tinker Bell with him as an ally. Tinker Bell is delighted to go with Sora as a summon.

If one returns to Neverland, Tinker Bell tells Sora and Peter of the Phantom Heartless at the clock tower.