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 Jackie Buscarino Susan Strong, Kara Guest Voice Niki Yang BMO Guest Voice Lennon Parham Dr. Gross Guest Voice Livvy Stubenrauch Young Kara Guest Voice Jasika Nicole Frieda Guest Voice Stephen Root Martin Guest Voice Sharon Horgan Minerva Guest Voice ViviAnn Yee Young Frieda Guest Voice Fred Seibert Executive Producer Kelly Crews Producer Hanna Nystrom Writer Aleks Sennwald Writer