Olivia Rose Olson 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.
Olson was adopted at birth and raised in Los Angeles, California. She lives with her father, Martin Olson, mother, and brother. Olson graduated from Agoura High School in 2010. She is of Jamaican and Swedish descent.