Olivia Rose Olson is an American actress, voice actress, and singer-songwriter, who is mostly known for voicing Marceline the Vampire Queen in Adventure Time. She also played the character of Joanna in the 2003 film, Love Actually and its 2017 short sequel, Red Nose Day Actually.
For Disney, she voiced Vanessa Doofenshmirtz on the Disney Channel animated series Phineas and Ferb. She has also sung multiple songs as Vanessa in Phineas and Ferb, including a catchy duet called "Busted" with co-star Ashley Tisdale. Additionally, she sung "I'm Lindana and I Wanna Have Fun!" as Linda Flynn and "Ready for the Bettys" as The Bettys.