Perhaps Dr. Banzai?
A fact which was alluded to in The Expendables 2.
Ken Jeong from The Hangover movies and Community is an M.D.
Auto racing and college football commentator Jerry Punch is an M.D. He administered first aid to NASCAR drivers Rusty Wallace and Ernie Irvan after serious crashes while working as a pit reporter.
TV host and comedian Matt Iseman (Clean House, American Ninja Warrior) is an M.D.
Yes, I know this thread is seven years old, but since it was posted, Brian May was awarded his doctorate in 2008. So you may now call the composer of “Fat Bottomed Girls” Dr. May. 
Ditto-- since the thread was started, Mayim Bialik has finished her Ph.D in neurobiology. Her dissertation topic was the role of the hypothalamus in Prader-Willi syndrome. I’d actually read that dissertation.
In addition to what I said in post #98 (which wasn’t quite correct), let me note that there is now a book about the invention of frequency-hopping, Hedy’s Folly by Richard Rhodes.
The interesting thing is that Mayim Bialik has a Ph.D. in neuroscientist and plays a neuroscientist. It appears to me from the news stories I’ve found that Dolph Lundgren didn’t use his chemical engineering degree in Expendables 2. In fact, he apparently suggested that the filmmakers change a scene because it wouldn’t work scientifically, and they ignored him.
Don’t know what scene you’re referring to but in the one I’m thinking of, his character’s idea did not work.
For what it’s worth, jokes do manage to survive the editors and get into citation lists. My old advisor and his (then) postdoc once managed to slip in a citation to Scotty, the Enterprise’s engineer. I’m still not sure if it survived peer review because the reviewers got it, or because they didn’t.
Dr. Victoria Zdrok. B.A. age 18, J.D., PhD. Clinical Psychology, Playboy Playmate of the Month Oct 1994, Penthouse Pet of the Year 2004, and adult film star. VA VA VOOM!!
Vitali and Wladimir Klitschko, brothers who each have held a world heavyweight boxing title, also both have PhD’s in physical education from Kyiv University of Physical Science and Sports. Vitali is now Mayor of Kyiv.
Woody Paul Chrisman, the fiddle player in Riders In The Sky, has a Ph.D. in theoretical plasma physics from MIT.
Skywatcher, various news stories say that Lundgren told the filmmakers that their idea for a bomb wouldn’t work and they ignored him:
And from what I understand he maintains all his credentials and is fully licensed in California.
And the bomb didn’t work as intended so I don’t know what your point is.
Ronan Tynan of the Irish Tenors, formerly the New York Yankees’ “God Bless America” singer, is an MD with a prosthetics practice. He is also a multi-medalist at the Special Olympics in track events, despite having no feet.
Extremely successful, in fact: He was a self-made orphan (er, an orphan and self-made millionaire) who was actually richer than his successor, FDR.
Did they source him as an authority of the fact that you cannae change the laws of physics?
“Dead or Alive, turn your head to the left and cough…! Would you like me to check your… motility?”
“Jeez, doc, your hands are freezing…!”
“Come quietly or there will be… trouble…”
The most surprising one that I know of is former NBA star Shaquille O’Neal. He received his doctorate in education in 2012.
She plays a neuroscientist, but her degree is in neurobiology. There’s some distinction. I think her actual field is the biological bases of behavior, while her character studies neurons, or organ structures (eg, the hypothalamus) composed of neurons. I heard her discuss it in an interview once, but my personal experience is limited to a single neurobiology class I took in college to fulfill a science requirement. I also needed a 300-level class, and it sounded interesting. It was for biology/psychology (cross-listed) majors, and the math was a little above me, and I got a C- (but if I’d gotten a D-, still would have counted). It was my senior year. Anyway, the class was very interesting. Our grade was based on scores on four exams, and that was it, or I probably would have done better. I remember a lot of the information, like labeling the structures in the brain, but the math problems regarding balancing sodium chemistry…*…choke…did me in.