|Voiced by||Olivia Olson|
|“||Daddy, why did you eat my fries?||”|
Marceline is a thousand-year-old vampire who just likes to have some fun, but sometimes can't because of her troubled past. Marceline has lived in many different houses, including Finn and Jake's treehouse, as she from time to time tries to escape from the notice of the Ice King, who nevertheless always finds her again. Marceline's house is currently in a cave.
Marceline first appeared in FusionFall Heroes, but was added to the main game for the "Nightoween" Halloween 2013 event in Peach Creek Commons where a portal has opened to the Nightosphere, where Marceline's father, Hunson Abadeer, sells the player objects from Adventure Time.
- Bonewing Marceline - Wears bone batwings
- Sunscreen Marceline - Wears her wide floppy hat
- Sweet Marceline - Wears Princess Bubblegum's crown and carries a lollipop
- Queen Marceline - Has the Marceline Transformed monster head and carries Valhallen's Axe
- Ice Cold Marceline - Wears the Ice King's Crown and carries an Ice Axe
Vampire Axe Mordecai also carries Marceline's axe, so she must loan it or a copy of it to him from time to time.