Which character did a member of the cast of "Love Actually" voice in "Adventure Time"?
Olivia Olson: Olivia Rose Olson (born May 21, 1992) is an American actress and singer-songwriter, mostly known for her voice roles as Vanessa Doofenshmirtz in "Phineas and Ferb" and Marceline the Vampire Queen in "Adventure Time". Red Nose Day Actually:  "Love Actually" writer and director Richard Curtis returns alongside cast members Hugh Grant, Liam Neeson, Colin Firth, Andrew Lincoln, Chiwetel Ejiofor, Keira Knightley, Martine McCutcheon, Bill Nighy, Thomas Sangster, Lúcia Moniz, Olivia Olson, Marcus Brigstocke, and Rowan Atkinson.
Marceline the Vampire Queen