Sebastian Stan is a Romanian American actor, known for his role as James "Bucky" Barnes / Winter Soldier in Captain America: The First Avenger and Captain America: The Winter Soldier. He played The Mad Hatter/Jefferson on the ABC's fantasy drama Once Upon a Time, Prince Jack Benjamin on Kings and Carter Baizen on Gossip Girl. He also appeared in Black Swan. In 2012, he appeared in the USA Network miniseries Political Animals starring alongside Sigourney Weaver.
His role in Political Animals earned him a nomination at the Critics' Choice Television Award for Best Performance by a Supporting Actor in a Miniseries.