Beast Chimera (ビーストキマイラ Bīsuto Kimaira) is an ancient cannibalistic Phantom who is Kamen Rider Beast's Enslaved Phantom (使役ファントム Shieki Fantomu) ally Chimera (キマイラ Kimaira). Unlike WizarDragon, who was born from within Haruto, Beast Chimera was mysteriously imprisoned in the Beast Driver until it was discovered by Kosuke himself and entered his Underworld while forming a pact with the human, where in exchange for using his Mana, Beast must absorb the mana of defeated Phantoms for Chimera, or Kosuke will pay with his life for failing.