It' Anna. I know a lot of you think Ellie is pregnant because of that one poster, but in the second one, Ellie has short hair and the girl in the poster doesn't. Also, remember in the first one, Ellie doesn't need a gas mask. She's immune! I really think that's Anna. Don't you??? Maybe you get to play as Anna in one part of the game ands that's why it shows her on the poster.