The actress played Karen in the 2004 high school comedy.
Amanda Seyfried revealed how Mean Girls had the potential to be much different. During an interview with Vanity Fair, the actress, who played Karen in the 2004 high school comedy, said that Blake Lively almost had her role.
While watching clips from the film, Seyfried reflected on the moment she went in to audition for the movie, which also stars Lindsay Lohan, Lacey Chabert and Rachel McAdams. Prior to landing her role, she initially went out for Regina George -- famously played by McAdams.
"I had first auditioned for Regina," she says. "I had flown out to LA for the first time with my mother, it was very exciting. I met Lacey Chabert for the first time and Lindsay Lohan was in the room and Blake Lively was playing Karen and then I was Regina."
Seyfried shared that after flying home, she received the call that the casting team had her in mind for Karen.
"I flew home and they were like, 'You know what, we think you're more correct for Karen.'"
And the rest is history. Lively, of course, didn't star in the film, and Seyfried as Karen played alongside Lohan (Caty Heron), Chabert (Gretchen Wieners) and McAdams (Regina George) as the infamous Plastics.
Seyfried shared why she believes she got the role.
"I was so present and it was such an enlightening and fulfilling experience," she says. "I was so clueless I think the reason I got Karen was I played that person in high school in order to stay out of any drama. It was a much easier transition to play Karen from that point in my life. I was only 17, high school was right there."
The 37-year-old actress reflected on working with the other young women in the film.
"I don't know how we created our dynamics for the Plastics, we all came from different places, we were different ages," she says. "Lindsay and I were the closest in age and Lacey was a few years older and Rachel was a few years older than Lacey. I remember the feeling of everybody really wanting to be there and everybody appreciating the ingenious of the script."
She adds, "I remember everybody just having a lot of fun. There was such a vibe. They casted right. We were all pretty cool people, pretty happy people and Mark Waters was an amazing director, he made it so fun."
Fans of Mean Girls will have the chance to see the iconic characters come back to life with the release of the musical movie, based on the play -- which, like the film, was written by Tina Fey.
The ensemble cast for the new film, which is being made for Paramount+, includes Angourie Rice (as Cady), Reneé Rapp (as Regina), Auli'i Cravalho (as Janis), Jaquel Spivey (as Damian), Tina Fey (as Ms. Norbury), Tim Meadows (as Principal Duvall), Avantika (as Karen), Christopher Briney (as Aaron), and Bebe Wood (as Gretchen).
When it comes to any of the original Plastics joining Fey and Meadows as they return to the film, ET has learned that any of the original Mean Girls cast returning for the new flick is yet to be seen.
Seyfried, on the other hand, wouldn't mind being called to be part of the fun. In January, the actress dished to ET about the possibility of joining the musical movie.
"I don't know, I don't know," the actress told ET. "I truly, honestly don't know for sure, but I'm very open to it. It's evolved so much over the years. I mean, it's still so beloved, and I don't see it ever ending. I hope it never stops evolving."
Renee Rapp Reacts to Amanda Seyfried Being 'Open' to 'Mean Girls' Musical Film Cameo (Exclusive)