Guest Stars Hynden Walch voices Bonnie Olivia Olson voices Marceline Audrey Bennett voices Young Marceline Stephen Root voices Martin Mertens Jenny Slate voices Huntress Billy Brown voices Vampire King Jeremy Shada voices Baby Finn Erica Luttrell voices Hana Abadeer Co Starring Dee Bradley Baker voices Additional Voices Cree Summer voices Additional Voices Jinkx Monsoon voices Additional Voices Steve Little voices Additional Voices Cole Sanchez voices Additional Voices