The original Penny on The Big Bang Theory was a very different character, but never made it past the unaired pilot. Kaley Cuoco played the only main female character in the series in its first three years, acting alongside Jim Parsons (Sheldon), Johnny Galecki (Leonard), Simon Helberg (Howard), and Kunal Nayyar (Raj). It wasn't until season 4 that the show brought in Melissa Rauch's Bernadette and Mayim Bialik's Amy, which not only expanded The Big Bang Theory's cast, but also increased the female representation in the sitcom. However, Penny does appear from the very first episode in 2007.

Prior to The Big Bang Theory's official premiere, its unaired pilot had a significantly different cast of characters aside from Leonard and Sheldon. Penny, Raj, and Howard are missing, and in their place are two other female characters. Gilda, played by Iris Bahr, is reminiscent of Sara Gilbert's Leslie Winkle,...