Pendleton Ward Lumpy Space Princess Creator, Voice Jeremy Shada Finn Voice John DiMaggio Jake Voice Hynden Walch Princess Bubblegum Voice Tom Kenny The Ice King Voice Olivia Olson Marceline Voice Niki Yang BMO, Lady Rainicorn Guest Voice Fred Melamed Gumbald, Punchbowl Guest Voice Hayden Ezzy Fern, Grass Demon Guest Voice Justin Roiland Earl of Lemongrab Guest Voice Sean Giambrone Shermy Guest Voice Willow Smith Beth Guest Voice Tom Scharpling Jermaine Guest Voice Maria Bamford Aunt Lolly, Slime Princess Guest Voice Felicia Day Betty Grof Guest Voice Fred Seibert Executive Producer Kelly Crews Producer Tom Herpich Writer Steve Wolfhard Writer Seo Jung Kim Writer Somvilay Xayaphone Writer Hanna Nystrom Writer Aleks Sennwald Writer Sam Alden Writer Graham Falk Writer