Giancarlo Esposito is certainly playing someone in upcoming Marvel sequel Captain America 4, but everyone is super in the dark as to who. Not even the movie's first teaser explicitly identified him, despite the fact that he features a fair bit in it...
Since, fans have been practically placing bets as to who the Better Call Saul star's character is online, throwing out suggestions like X-Men associate and gun-toting SHIELD agent G.W. Bridge. According to the actor, though, no one has accurately guessed right so far.
