Alexander Greenwald is an American musician and actor. Prior to his music career, he began his professional career as a teen actor with both live-action and animated roles in films like The Halloween Tree (1993) and No Dessert, Dad, till You Mow the Lawn (1994), before primarily transitioning to a music career shortly after, and has been the frontman and rhythm guitarist of the California rock band Phantom Planet since their inception in 1994. Greenwald has also been a member of Blackblack and the indie pop supergroup Phases and is a frequent collaborator of the British musician, DJ and producer Mark Ronson. Greenwald released a solo album, Yo, in 2014 and played a minor role in then-fianceé Brie Larson's 2017 film Unicorn Store.