William Gregory Magnussen (born April 20, 1985) is an American actor.
Magnussen starred in his breakout role as Rapunzel's Prince in Rob Marshall's 2014 film Into the Woods. In 2016, Magnussen appeared in The Great Gilly Hopkins, opposite Kathy Bates, as Ellis, the social worker in charge of Gilly Hopkins, played by Canadian actress Sophie Nelisse. The role was originally written for a female in the novel and stage play. In 2017, Magnussen was cast in a newly created role as Prince Anders in Disney's live-action adaptation of Aladdin directed by Guy Ritchie.