WizarDragon

WizarDragon is the inner Phantom of the Kamen Rider series, a type of monster that emerges from Gates, magically endowed people when they fall into despair.

History
When Haruto Sohma lost his parents at a young age, the feelings of despair gave birth to Dragon yet he remained in a state of inactivity until Haruto was taken for ritual that created the Phantom with the sacrifice of hundreds of Gates. However, though Dragon was close to ripping his host from the inside out, Haruto suprassed his inner Phantom's birth by facing his despair head on. Since then, with Haruto able to use magic and fighting the borned Phantoms as Kamen Rider Wizard, the renamed WizarDragon was forced to remain in Haruto's Underworld until summoned to fight other inner Phantoms into the Underworlds of other Gates. And even then, the Phantom refuses to directly obey Wizard

However, when Haruto turned to him for help against a Phantom named Phoenix, WizarDragon accepts his plea on delightful whim upon that his power is the human's last hope.

Trivia

 * WizarDragon is very similar towards Hollow Ichigo of Bleach;
 * They both are sealed inside the main protagonist whom they are an aspect of, who can call on their power.
 * They have no real alignment, attacking both good and evil.