It's very rare for anyone to start in the adult film world and then crossover to mainstream success. For every Jackie Chan & Sly Stallone, there are a ton of mainstream careers that were DOA. Even more rare are the celebrities who've attained mainstream success who then make the leap into the adult world, but it does happen, and it's almost always heartbreaking.
A thread started by user HillaB on Imgur (link below) spotlights a number of these crossover... superstar's not the right world, but you get the idea.
Jaimee Foxworth a.k.a. Crave
For four seasons, Jaimee played Judyy, the youngest member of the Winslow clan on Family Matters. When Foxworth asked for a raise following the fourth season, the show's producers handled her request like the mature, responsible adults they are: they wrote her out of the show. These days, she's appearing in adult films under the name Crave, and even made The Jeffersons: A XXX Parody in 2009, bringing her career full circle as her screen debut came on Jeffersons star Sherman Hemsley's follow-up series Amen.
Tom Sizemore
Despite a name tailor made for the porn industry, Tom Sizemore had a very successful acting career once he managed to prove that he wasn't Eldin from Murphy Brown. He even got to reprise his acclaimed role in Saving Private Ryan twice in both Pearl Harbor & Black Hawk Down. Tom's raging drug and prostitution problems eventually got the best of him, forcing him into porn and eventually into even more despicable avenues like Celebrity Rehab with Dr. Drew alongside such notably successful alumni as Mike Starr, Jeff Conaway, Mindy McCready, and Joey Kovar. He does appear to be doing just great now, however.
Stephen Geoffreys a.k.a. Sam Ritter
Stephen Geoffreys rose to prominence with roles like Evil Ed in Fright Night and Hoax in 976-Evil, but when the mainstream offers started drying up, Geoffreys changed his screen name to Sam Ritter and took the plunge, literally, into gay porn. Now, I haven't seen Butt Blazer or Leather Intrusion Case 4: Down to the Wire—I gave up on that franchise at part 3—but I can't imagine they're that much worse than 976-Evil.
Chyna
Speaking of Celebrity Rehab with Dr. Drew, former WWE Wrestler Chyna, most famous for possessing "a clit twice the size of my thumb" is another one of the only survivors of that horrific experiment that somehow lasted six seasons. After appearing twice in Playboy, despite being built like a brick shit house, Chyna sold a sex tape to Vivid and has since gone on to a surprisingly lucrative career in porn. There's truly no accounting for taste.
Scott Schwartz
He's at the center of one of the most famous moments in film history, and all you children of the 80s will definitely recognize Scott Schwartz from his roles in The Toy and Kidco. What you may not know is that Schwartz went on to a career in porn, but his porn career is something of an anomaly. See, he's appeared in such hardcore films as Scotty's X-Rated Adventures and The Wrong Snatch, but always in a "non-sexual" capacity. That's right, Scott Schwartz may be the only man alive whom you can legitimately call a porn actor.
Adam West
Well, maybe not the only man alive. Adam West is still with us, and while Scotty's tongue was still stuck to that flagpole, the man who would be Batman was appearing in several softcore classics like The Happy Hooker Goes Hollywood and Young Lady Chatterly II, but always in a non-sexual capacity. Perhaps it truly was the Noid who should have avoided Adam West.
Via Imgur