Caitlin FitzGerald (born August 25, 1983) is an American actress and filmmaker. She is best known for her role as Libby Masters in the Showtime television drama Masters of Sex (2013–2016) and as the elusive Simone in Starz series Sweetbitter (2018–2019). She has appeared in Love Simple (2009), It's Complicated (2009), Gossip Girl (2011), Damsels in Distress (2011), Blue Bloods (2010), and Newlyweds (2011).