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 7 of 12 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 7 The band was most famous for making The O.C.'s theme song, "California" — here's Alex hanging out with the cast. You definitely know it. Previous Next Start Slideshow Brie LarsonCelebrity CouplesAward SeasonOscarsCelebrity FactsAlex Greenwald