Olivia Rose Olson (born May 21, 1992) is an American actress and singer-songwriter. She is mostly known for her voice roles as Vanessa Doofenshmirtz in "Phineas and Ferb" and Marceline the Vampire Queen in "Adventure Time", Nutri Ventures, Bliss from Craig McCracken's "The Powerpuff Girls" franchise. She also played the character of Joanna in the 2003 movie "Love Actually" and its 2017 short sequel "Red Nose Day Actually".