Jo, also known as Bunny Girl, is a human that was first seen in "Everything Stays," during Marceline's flashbacks. She was part of a human tribe and was first afraid of Marceline and had mistaken her for a vampire (at a time before she got turned). However, they quickly become friends as Marceline got accepted by the human tribe.
Jo is a regular female human with a hat that has long bunny ears and a cape over her neck dropping down to her legs. The cape and hat have both the same shade of white. She also wears a light blue t-shirt that is torn above her belly button and blue shorts. Her hair is brown in color. Her skin has a low tanned tone, and seems to be barefoot.
Jo was always hyper, playful and although easily frightened of her, gained trust of Marceline later on. She seemed to have a liking in music as she asks Two Bread Tom to play a song on his guitar and Marceline to continue the song on her ax base.
- In pre-production, she was a boy, and her name was Graham.
- Jo stars in the Adventure Time graphic novel "Islands."