Acting muscles

Serena Williams

Can kick your ass at: Tennis.

Trophy case includes: Two Olympic gold medals and 18 Grand Slam titles. Sibling rivalry can be a great motivator (her older sister is tennis star Venus Williams).

Went Hollywood for: Guest spots on “My Wife and Kids,” “Law & Order” and “ER,” as well as a voice-acting gig on Nickelodeon’s “Avatar,” which she claimed was her favorite show. Wow, an athlete giving an endorsement for free!