Shelby

Shelby Butterson (voiced by Pendleton Ward) is the worm who lives in Jake's Viola who first appears in "My Two Favorite People" and later returns in "Video Makers." He can talk and lives in Jake's viola. In "My Two Favorite People," he gives Jake the idea to hang out with Finn and Lady Rainicorn at the same time. He has the same tone of voice as Manfried. He also makes a cameo in "What Was Missing" when he crawls in and out of Jake's viola, and narrates the ending of "Holly Jolly Secrets Part II," where he and the general cast watch videos and wear sweaters. In the winter, he wears a green sweater with two candy canes on it. He appears in "Five More Short Graybles" reading a book while sitting on Cranky Cookie's statue, and has a major role in "Mystery Dungeon."

It should be noted that Shelby appears as an earthworm, and although earthworms are hermaphrodites he is a male as confirmed by Pen Ward.