Thromnambular is a wishing skull. He first appeared in Wishbones. He gave wishes to some of the characters. Later on in Wish Unfulfillment it is revealed that he became a genie to get his wishing powers back. He always speaks in rhymes throughout the episode; he also assumedly can't grant wishes to people who already used one.
- Billy wished for a life of adventure which was like a Johnny Quest spoof (even recycling a piece of music from the show). It ended with Irwin being eaten, Billy badmouthing the adventure they had, and Harold grounding Billy for saying such things.
- Harold wished that he would live back in his high school days. He ends up being constantly shoved in a trash can.
- Skarr wished to be lord high ruler and supreme dictator of all humanity. He rises up on a statue of himself, which reaches all the way into space, where he dies and explodes from lack of oxygen.
- Irwin wished he could be in the music industry with Mandy. Of course, Mandy rejects him once more.
- Pud'n wished he could have a bunny to love him "to death". But the bunny loves him a little too much, to the point where he tries to kill him, claiming he was doing so because "Love hurts, Pud'n, and I love you a lot."
- Nergal Jr. wished he knew what he wished for so he wasted his wish.
- Sperg wished he could go into the girls' room to steal money from a rich girl. He overhears the girls making fun of him, which makes him cry and fail.
- Mindy wished she could be a star. She gets launched on a rocket into space.
- Grim wished the kids had never found the skull, undoing all of the other wishes.
- Grim In the epilogue, wishes himself free of Billy and Mandy and that Thromnambular never has to grant another wish. Thromnambular transfers his wish curse to Grim's skull and takes over Grim's body as the new Grim Reaper.