Sebastian Stan ( born August 13 , 1982 ) is a Romanian-American actor , known for his role as Bucky Barnes / Winter Soldier in the Marvel Cinematic Universe . On television , Stan portrayed Carter Baizen in Gossip Girl , Prince Jack Benjamin in Kings , Jefferson in Once Upon a Time , and T.J. Hammond in the miniseries Political Animals . His role in Political Animals earned him a nomination for the Critics ' Choice Television Award for Best Supporting Actor in a Movie/Miniseries . In 2015 , he co-starred in Jonathan Demme 's Ricki and the Flash , Ridley Scott 's The Martian , and Bryan Buckley 's The Bronze .
Sebastian Stan had a role in a TV production.