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

Ever since her early 2000s breakout role as Bridget Hennessy in the John Ritter sitcom "8 Simple Rules," the trajectory of Kaley Cuoco's career has only gone up. After 12 years as Cheesecake Factory waitress Penny on CBS' "The Big Bang Theory," she helmed "The Flight Attendant," the animated series "Harley Quinn" and a slew of others.

Some fans might not realize that, in many of her projects, the actress' little sister Briana Cuoco makes appearances. This is true for "The Flight Attendant," in which she plays the role of Cecilia, and "Harley Quinn," which sees her voicing numerous characters, including Batgirl. Some credits specific to the younger Cuoco include "The Bold and the Beautiful" and the forthcoming "Dead Boy Detectives," based on the DC comics (via IMDB).

In 2013, she also tried to make a name for herself in the music industry and competed on NBC's "The Voice." After joining Team Christina Aguilera, she advanced several rounds but eventually found herself up for elimination. She was given a second chance by Blake Shelton, yet her performance of No Doubt's "Don't Speak" during a match-up round ultimately sent her home (via Today).

Her big sister supported her dreams and was even the one who urged her to try out for "The Voice," as told to extratv. There seems to be much sibling love between the Cuoco girls. However, during a shared scene on "The Big Bang Theory," the characters aren't exactly best friends.

In Season 6, Episode 16 ("The Tangible Affection Proof"), the group is struggling to enjoy the perfect Valentine's Day. Sheldon (Jim Parsons) is clueless about what gift to give Amy (Mayim Bialik), Howard (Simon Helberg) and Amy (Melissa Rauch) are in a tiff over laundry, and Raj (Kunal Nayyar) and Stuart (Kevin Sussman) plan a party for fellow singles.

Meanwhile, Leonard (Johnny Galecki) is trying to give Penny the perfect date night, but during their romantic dinner, she spots her old flame and the woman he cheated on her with — Gretchen, played by Briana Cuoco. Penny, who hates the fact that Gretchen lost weight and looks good, is livid when her ex proposes at the restaurant.

Cuoco's spot on "The Big Bang Theory" may be brief, but she made a lasting impact on set. Fans might remember the viral flash mob dances performed by cast and crew to Carly Rae Jepson's "Call Me Maybe" and other pop tracks. All flash mobs were choreographed by Cuoco and became bigger each year. In an interview with ET, she revealed which "The Big Bang Theory" stars were her best dance pupils. "You know who kind of kills it is Mayim. Mayim slays it. And Kunal," she said. "I will say that Jim had flashcards. He would write down all the choreography..."

Hopefully, if the show's cast ever does a reunion, Cuoco will be asked to coordinate a new routine. Until then, with several projects on the horizon, the world can watch as she maps out her own unique career.