For various reasons, a lot of celebrities don't finish high school.  But there's something cool about the ones who go back and get their GEDs, even though they really don't need an education to earn a living anymore.

With that in mind, here's a list of celebs who did just that . . .

Katy Perry

50 Cent

Michael J. Fox

Paris Hilton

Pink

Jessica Simpson

Christian Slater

Mark Wahlberg

Angelina Jolie

Ja Rule

Jamie Lynn Spears

Tobey Maguire

Carrie Fisher

Mary J. Blige

Michelle Rodriguez

Rob Thomas

Gretchen Wilson

Bam Margera

Bill Cosby

(Christina Applegate and Nicolas Cage are also on the list, although technically, they didn't go BACK to school.  They took the test as juniors, and were able to graduate early.)

(Check out a photo gallery of all the graduates here.)