Lucifer

Lucifer is Lady Tremaine's cat, first appearing in Kingdom Hearts Birth by Sleep. He originated in the classic 1950 film .

Kingdom Hearts Union χ
In a projection of the future, as Jaq and gather materials for Cinderella's gown, Lucifer appears and steals the bead necklace from Jaq. They chase Lucifer around the estate until cornering him in the upstairs corridor. A trio of Heartless appear, frightening Lucifer, who drops the beads and runs off.

Kingdom Hearts Birth By Sleep
Ventus heads back to the wardrobe room to find the last last item to complete Cinderella's dress, a pearl. However, Jaq stops him and warns Ventus about Lucifer, who is a very mean cat. Ventus is confident that he can handle a cat even at his diminutive size and leaves.

Ventus finds Lucifer sleeping in the wardrobe room, right in front of the pearl they need to finish the dress. As Ventus takes it and creeps back to the mouse hole, Lucifer awakes and prepares to strike Ventus from behind with his claws for interrupting his sleep. However, Jaq warns Ventus at the last minute and throws balls of string at Lucifer to distract him, but Lucifer rams himself into the cabinet where Jaq was standing and causes Jaq to fall onto the floor. As Lucifer prepares to kill Jaq, Ventus intervenes and strikes Lucifer's paw with his Keyblade. Ventus sends Jaq to safety with the pearl while he fends off the cat. Finally, Lucifer gets a beating from Ventus, making the cat run from the room.

Design
Lucifer is an obese cat with dark brown fur covering most of his body. The fur on his belly, his paws, and the tip of his tail is tan. The fur on his head is ruffled and black. Lucifer's eyes are green and his sclera are yellow, while his nose is pink. He has two whiskers on either side of his upper lip.

Abilities
Lucifer himself has no special powers of his own, but he attacks by using his claws. He is quite agile, able to leap from higher parts of the room to body slam opponents. He can also charge at Ventus if angered.

Origin
Lucifer is a ferocious cat from the 1950 Disney film, . A nemesis to Cinderella's mice friends and the other animals living on Lady Tremaine's estate, he is pampered and praised by the elderly lady. While the two stepsisters and the wicked stepmother fail to realize Lucifer's evils, he never manages to avoid the protective and watchful eyes of one person, Cinderella herself. She has a secret weapon used for dealing with the devious cat, however; her loyal dog Bruno. At the film's climax, he again tries to catch both Jaq and Gus while they are trying to free Cinderella from her locked room, but the birds see this and summon Bruno, who saves the mice by scaring Lucifer. The cat manages to escape from Bruno by jumping out of a window. Although Lucifer was initially believed to have died from the fall, he appears to be still alive and well in the film's two sequels.

Trivia

 * Despite his journal entry giving him the name "Lucifer", his name is never pronounced correctly in the game, to the point that even Ventus calls him "Roosafee", which is how Jaq pronounces it.