Who Did Kaley Cuoco's Sister Briana Cuoco Play On The Big Bang Theory?

Briana Cuoco, sister of Kaley Cuoco who plays Penny in "The Big Bang Theory," appeared on the show as Gretchen, an enemy of Penny's in a Valentine's Day episode. During the episode, Penny spots her ex-boyfriend proposing to Gretchen, whom he cheated on her with.

Despite her brief appearance, Cuoco made a lasting impact on set by choreographing the cast and crew's viral flash mob dances to pop tracks like Carly Rae Jepson's "Call Me Maybe." In an interview with ET, she revealed that Mayim Bialik and Kunal Nayyar were some of the best dancers on set. Cuoco continues to work on new projects and establish her own unique career.