has she appeared on screen in any movies?
Yes, in "Love Actually"
Olivia Olson
Olson rose to fame for her role as Joanna Anderson in the 2003 holiday film "Love Actually", singing the song "All I Want for Christmas Is You"
who does the voice of marceline on adventure time Ava Acres, Olivia Olson, Cloris Leachman. who is this character? She's the protagonist of the show. She is a a half-demon and half-human vampire who assumed the title "Vampire Queen" after having killed the previous Vampire King. which show is this? "Adventure Time" has the second voice-actor worked on any other movies? She has lent her voice in the series "Phineas and Ferb".
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Olivia Olson [SEP] 2003: "Love Actually"
Olson rose to fame for her role as Joanna Anderson in the 2003 holiday film "Love Actually", singing the song "All I Want for Christmas Is You". Her singing was praised, with director Richard Curtis stating in the commentary in the music section of the "Love Actually" DVD that Olson's singing was so perfect, they were afraid the audience would not believe that a ten-year-old could really sing the way she did and would assume she was lip-synching to Mariah Carey's voice. They had to train her so her singing would sound more believable, and add the sounds of inhalations to the track.