All these actors were offered/considered for the following roles...
Alien-
Harrison Ford as Captain Dallas?
Veronica Cartwright as Ripley?
Jon Finch as Kane?
Aliens-
James Remar as Hicks?
Alien: Resurrection-
Ewan McGregor as Vriess? (At least when Boyle was attached)
Angelina Jolie as Call?
Bill Murray as Dr. Wren?
Chow Yun-fat as Christie?
I personally think the films and actors are fine the way they are, but these are interesting "what ifs".
