<P> 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 . She also played the character of Joanna in the 2003 film Love Actually and its 2017 short sequel Red Nose Day Actually . </P>
<P> 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 . She also played the character of Joanna in the 2003 film Love Actually and its 2017 short sequel Red Nose Day Actually . </P>
who sings all i want for christmas in love actually
who sings all i want for christmas in love actually
Olivia Rose Olson
Olivia Rose Olson