WHOA, Who Knew? 18 Celebrities Who Started Off As Porn Stars

Unlike most celebrities who try to keep their porn past under wraps, “The Girlfriend Experience” actress Sasha Grey flaunts it with no shame. She was already famous in the porn industry and continues to kill it in mainstream media with her acting, modeling, and music careers.

Before he was one of Hollywood's biggest actors, Channing Tatum was a male stripper under the name "Chan Crawford." Okay, so he didn't star in porn. But, did you know "Magic Mike" was loosely based on his stripper life? Now you do. 

Though she first became famous by association with Paris Hilton, the infamous Kim Kardashian became a household name after a sex tape of her and ex-boyfriend Ray J was distributed as a film. Though she sued and eventually dropped charges, it paved the way for her widely-known reality show, 'Keeping Up With The Kardashians'. Talk about seizing opportunities!

This Game of Thrones actress used to be a German porn star, so I'd definitely be wary of looking for any of her old movies.

Although she wasn’t a porn star per se, Marilyn Monroe did pose nude for photos during a short decline in her career. It was the only time she was paid for nude photos. Though the porn of those days was tame compared to today’s standards, she was still an internationally known sex symbol that everyone's husband, boyfriend, son, and next-door neighbor drooled over.

Before becoming an actor and writer, Spalding Gray appeared in three porn movies. He was too busy with his monologue work that would eventually make him famous.

The Internet is abuzz with claims that Dame Helen Mirren was once in a porno or two, and guess what? She's still classier than you and your mom.

From Starbucks to porn, Riley Steele was encouraged to join the adult film industry by porn star Jesse Jane. She got her big break in 'Pirates II: Stagnetti’s Revenge,' the sequel to the porn film 'Pirates'. Since then, she has had very few and small roles in mainstream movies and tv, including 'Piranha 3-D' and HBO’s 'The Girl’s Guide To Depravity.' Hey, at least she's paid more than as a Starbucks barista.

Before she was in Entourage, Perrey Reeves also starred in an episode of the soft core porn series Red Shoe Diaries.

Before he was Rambo or Rocky, Sylvester Stallone filmed a weird porno where he played the role of 'Stud.' Hey, porn isn't known for its well thought out writing, ok?

Matt Leblanc starred in an episode of David Duchovny's softcore porn series, The Red Shoe Diaries. That's the weirdest sentence I've ever written.

While he never starred in a porno, Jon Hamm worked as a set dresser. So if you've ever enjoyed the decor in a room during a porn movie, maybe you've enjoyed his work.

Jaime Pressley starred in Poison Ivy 3, which is either an erotic thriller or a softcore porn, depending on whether you talk to someone who worked on the movie or not.

This is another case of someone needing the money and doing what they had to do.  At least it wasn't his Rush Hour costar Chris Tucker. That would be a real nightmare.

David Duchovny used to star in a softcore porn TV series called The Red Shoe Diaries about a guy who people would send sexy letters to. He never filmed any sex scenes, he just did a lot of reading.

Cameron Diaz was in a softcore video before her big break came. Good thing, because looking at her these days, porn wouldn't have worked out.

The former governator allegedly posed for some pictures in the buff. I'd ask him if it was true, but I don't want to get flattened.

This is actually kind of sad. Before she was a hip-hop artist, fashion icon, and actress, Amber Rose performed striptease at only 15 years old to help her family after her parents' divorce left them financially disadvantaged.