Jest-O wears a black and blue jester outfit, has a large nose and wears yellow shaded eyeglasses. As a statue, his physique remains the same but his color palette is based on that of a statue.
Jest-O appeared at the front doorsteps of Omnibus' house asking for shelter in which the Warriors reluctantly agrees. He shows up with the Taunting Jester Magisword and forces the two to have fun by playing with the dishes, swimming in a tub filled with gelatin and fighting each other. He reveals that it was all the Taunting Jester Magisword's idea whose controlling him and them to have fun. The Warriors decided to get the sword away from him. After that, he unknowingly leaves at a bland pace. Omnibus later reveals that he has a statue shaped like a jester which obviously looks like Jest-O.
- He is voiced by series writer Doug Lawrence using a voice similar to his character Edward Platypus from Cartoon Network's Camp Lazlo.
- His voice is modeled after comedian Phil Silvers.