Oxford grad Hugh Grant ditched a potential career as an art history professor. David Duchovny abandoned his doctoral studies in English literature at Yale. That '70s Show star Ashton Kutcher gave up a biochemical engineering program at the University of Iowa.
But for some actors and actresses the jump between Hollywood and academia works the other way around.
Danica McKellar, who played girl-next-door Winnie Cooper on the '80s TV show The Wonder Years, and Ilan-Mitchell Smith, famous for creating his dream woman on the computer in the 1985 movie Weird Science, are just two examples of stars who have gone from the screen to the study hall.
"Films I knew I could always do later," McKellar said, recalling how she decided to pursue mathematics at UCLA. "I thought, 'I'm never going to go back and do math.'"
And McKellar didn't just go for it — she went all the way. In 1998, the girl known as Kevin Arnold's childhood sweetheart solved a math problem that had never been solved before.
Together with her professor and a fellow student, McKellar provided mathematical proof for a theorem dealing with magnetism in two dimensions.
"It could be helpful to physicists out there," she said. "You never know when a theorem will be needed. Sometimes mathematicians prove things and 100 years later it's useful."
Also working his way up the academic ladder is Mitchell-Smith, who played the nerdy-but-sweet Wyatt in the John Hughes comedy Weird Science.
"I made the decision to do it when I was 22," said Mitchell-Smith, who is pursuing a Ph.D. in medieval English literature at Texas A&M University. "I was all done with show business. I didn't want to do it anymore."
Mitchell-Smith says he gave up the spotlight for a variety of reasons.
"I was 16 when I did Weird Science. The only person close to my age was Anthony Michael Hall and I didn't like him all that much," he said. "They also referred to us as 'the talent' all the time. I never really was all that talented, and it wasn't my passion."
Mitchell-Smith, who is now more likely to be reading Chaucer than kissing supermodel Kelly LeBrock, said today he's recognized not for his looks but for his high, squeaky voice, which "unfortunately" hasn't changed much.
"My students don't always recognize me. This semester they did," he said. "It takes about a class period and then they get over it."
Mitchell-Smith may prefer English lit to Acting 101 now, but he said he'd still take a part if one were offered to him.
"Anybody would. The money's pretty good," he said, laughing.
As for McKellar, she's found a balance between math, writing, producing, directing and acting. Her second short film, Speechless, featuring Wonder Years dad Dan Lauria, recently premiered at the Cienquest film festival in California. She also wrote another movie, Talking in Your Sleep, which stars Wonder Years mom Alley Mills.
The brown-eyed star is also working on the forward to The Complete Idiot's Guide to Calculus, and serves as the spokesperson for a government-sponsored program, "Figure This!," which gives middle-school kids "real-world" math challenges. She also helps kids with their math homework on her Web site.
And McKellar and Mitchell-Smith aren't the only celebs sharpening their pencils.
Mayim Bialik, star of the sitcom Blossom, is working toward a Ph.D. in neuroscience. And Attack of the Clones star Natalie Portman, a Harvard student who is fluent in Hebrew, French and Japanese, recently told the New York Post that she's considered leaving show biz to become a vet or a clinical psychologist.
"I don't care if [college] ruins my career," Portman has said. "I'd rather be smart than a movie star."
Arthur Bartow, artistic director at New York University's Tisch School of the Arts, said it's difficult for an actor to imagine choosing to go into a totally different field.
"Most actors have been geared up to do this since they were 13," he said.
Aspiring English professor Megan Galbraith said she could kind of understand it.
"When I was younger I really wanted to do acting. My parents forced me into going into the academic route, which I wound up wanting to do anyway.
"But if someone offered me a role on a soap, I'd do it in a second," she said.