Amanda Seyfried
The role: Regina George in Mean Girls
Who *actually* played it: Rachel McAdams
The role they played instead: Karen Smith
Seyfried not only auditioned for the role of Regina, but she almost had it. Director Mark Waters said that she was "brilliant" as Regina, adding, "She played it in a much more ethereal, but still kind of scary way. She was more frightening, but oddly, less intimidating."