Popsugar Celebrity Oscars Who Is Brie Larson's Boyfriend, Alex Greenwald? Who Is Brie Larson's Beloved Fiancé? You Probably Already Know Him February 25, 2017 by Shannon Vestal Robson View On One Page Photo 5 of 12 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 5 Alex, 37, is a musician who you'd know best as the lead singer of the band Phantom Planet. Previous Next Start Slideshow Brie LarsonCelebrity CouplesAward SeasonOscarsCelebrity FactsAlex Greenwald