Rachel McAdams was initially told she was "too old" to star in Mean Girls.

The 47-year-old actress auditioned for the role of Cady Heron in the 2004 teen comedy film - but she was overlooked for the role in favour of Lindsay Lohan, and Rachel ultimately landed the role of Regina George instead.

Speaking to People, Rachel recalled being told by Mean Girls director Mark Waters: "You're too old to play Cady, but you're just right for Regina. Regina has been around the block a few times and maybe has a, I don't know if I'd call her an old soul, but she's got a few more miles on her than Cady'. So I took it as a compliment."

Rachel actually entered her audition with very low expectations.

The movie star shared: "I was just starting out, and it was the main character.

"I just did not think I was at that point in my life where I would be chosen for that. So I just kind of went in and had fun."

Rachel was ultimately thrilled to land a role of any kind in the film, as she assumed that it would become a huge success.

She said: "I loved the script so much. I remember closing that script and calling up my manager and saying, 'Please, even just playing a character that has one line I would take.'"

Meanwhile, Rachel recently confessed that she "didn't know how hated she would be" for playing school bully Regina in Mean Girls.

The actress wasn't prepared for Mean Girls to become a pop culture phenomenon - nor did she anticipate the level of hatred that came the way of her on-screen character.

Appearing on The Graham Norton Show, she said: "I didn't know how hated she would be and for how long.

"The first time I saw the film with an audience I was with my best friend. Everyone cheered when Regina was hit by a bus, but my friend stood up and screamed, 'Nooooo!"