…Cady Heron, which eventually went to Lindsay Lohan. Oddly enough, Mean Girls was originally set up with Lohan as the villain, but after the success of her and director Mark Waters’ remake of Freaky Friday, they scrapped those plans. Waters told Vulture,

“[Freaky Friday] was a much bigger hit than we expected it to be. Sherry Lansing, who was heading Paramount at the time, told us, 'We have to have Lindsay play the lead in Mean Girls. It's just not going to work having her play the villain, because she now has an audience that won't accept that.'"

McAdams’ age — she was around 25 years old when she auditioned for the role of a high schooler — both lost her the role of Cady and was a deciding factor for her landing Regina. Waters explained,

"I remember watching her do the scene, and after it was over, I told her, 'I think you're a movie star, but you're way too old for this character. You just aren't going to be able to play the ingenue.' And she said, 'No, I understand, I get it.'"

"When Lindsay was acting with Rachel, she got very shy, because Rachel was older and a very accomplished actress. She'd come in the room and not talk to Lindsay -- she was very focused. Lindsay kind of got nervous around her, and I thought that, more than anything, was going to be the deciding factor, the fact that she affected Lindsay in that way."

Amanda Seyfried also tested for Regina, but her take on the character was somehow "more frightening, but oddly, less intimidating." Seyfried would go on to be cast as The Plastics' ditziest member, Karen.