Letting yourself age naturally in Hollywood has pretty much become taboo — and while a lot of celebrities never fess up to getting plastic surgery, it's not hard to see who's gotten too much of it.

Friends star Courteney Cox completely changed her looks over the years, and not for the better, which is something she's willingly admitted.

RELATED: Khloé Kardashian Then and Now — See Her Complete Transformation!

"I think there's a pressure to maintain [your looks], not just because of fame, but just, you know, being a woman in this business," she said. "Getting older has not been … I don't think it's the easiest thing… I have done things that I regret, and luckily they're things that dissolve and go away. So that's good, because it's not always been my best look.”

Unfortunately, the actress is just one of many celebrities who has gotten work done to her face in an attempt to keep up with Hollywood's standards of beauty. Though others haven't been so keen to own up to it. Stars like Megan Fox and Naya Rivera look completely different from how they looked just a few years ago, but have adamantly denied getting fillers or botox. Let's just say, the photos speak for themselves.

Click through the gallery to see before-and-after pics of celebrities who have completely changed their faces over time.