EXCLUSIVE: Now that Marvel Studios and director Joe Johnston have set Chris Evans to play the title role in The First Avenger: Captain America, the other roles have begun to fall into place. Sebastian Stan is about to be fill the role of Bucky, the sidekick who fights side by side with the shield-throwing superhero. Stan is best known for Gossip Girl and he just completed the Darren Aronofsky-directed Black Swan and the Todd Lincoln-directed The Apparition. He also was just seen playing the nemesis in Hot Tub Time Machine. Studio confirmed Stan will be in the film in a deal that has multiple options, but there is no confirmation on whether Bucky transforms into Winter Soldier, as is the case in the Marvel Comics version. Marvel is also close to setting the female lead role of Peggy, and recently tested Keira Knightley, Alice Eve and Emily Blunt for that role.