Sebastian Stan (born August 13, 1982) is a Romanian American actor. On television, he has played Carter Baizen in Gossip Girl, Prince Jack Benjamin in Kings, Jefferson in Once Upon a Time, and T.J. Hammond in Political Animals. The latter earned him a nomination for the Critics' Choice Television Award for Best Supporting Actor in a Movie/Miniseries.

Stan gained wide recognition for his role as Bucky Barnes / Winter Soldier in the Marvel Cinematic Universe, beginning with 2011's Captain America: The First Avenger and later also in Captain America: The Winter Soldier (2014), Ant-Man (2015), Captain America: Civil War (2016), Black Panther (2018) and in Avengers: Infinity War (2018). In 2015, he co-starred in Jonathan Demme's comedy-drama Ricki and the Flash and Ridley Scott's science fiction film The Martian. Two years later, he portrayed Jeff Gillooly in the biopic I, Tonya.