Kibosh

Kibosh is a recurring villain in the Casper the Friendly Ghost franchise. Kibosh is the king of the ghosts and the ruler of the spirit world, compared to all the other ghosts in the franchise he is very different: he is green instead of white or blue with red eyes and a deep booming voice, also he is much larger than the other ghosts, and can even use his powers to become a giant.

Kibosh is the most powerful ghost in the world and as a feud with Casper's uncles, due to them skipping his ghost training academy (where ghosts learn how to haunt humans or "fleshies" as the ghosts call them). He also dislikes Casper for being so friendly since ghosts are supposed to scare humans so that they don't "rise up against creatures" and as such wants to banish the trio and Casper to either The Dark or The Valley of Shadows.

He debuts in the film Casper: A Spirited Beginning where he learns that Casper accidentally skipped ghost training and was being taught by the trio (whom he hated), and so he and his cowardly assistant Snivel (who fears him) decided to banish all four of them. He serves as the main villain of the film, though after Casper saves a boy's life, he decided to let him and his uncles off the hook.

Kibosh and Snivel return in Casper's Haunted Christmas, where they threaten to banish the four ghosts to The Dark, due to the fact that Casper does not scare humans (Casper replies that he does but Snivel says "But you don't mean to, so it doesn't count"). Kibosh and Snivel banish them to a town to scare someone and let them go near the end of the movie when Casper scares his uncles.

Kibosh also appears without Snivel in the game Casper's Spirit Demensions (where he tries to take over the world) and Casper's friends around the world (where he tries to get rid of Casper's human friends so he can make him into a true, scary ghost), he also appeared in the final film and its spinoff TV series Casper's Scare School.

Trivia

 * Kibosh was once a friendly ghost at Casper's age, it was revealed in Casper's Scare School.