Grim (DwtDS)

Grims (plural, Grim), are an ancient and powerful species of Dark Realm denizens that are comparable to Demons and capable of wielding a Keyblade, although they are preserved and enhanced by the power of Darkness they are ensured greater endurance via having human bodies - similar to Higher Nobodies and unlike Heartless or Unversed, Grims were believed to have gone extinct during the Keyblade War.

Ventus becomes a Grim in the Deal with the Devil Series, and seeks to complete his deal to save his friends, by making Sora one too.

Trivia

 * In Fairy myths, Grims are spirits of Black Dogs that guard Burial zones.