Why The Original 'Penny' In Big Bang Theory Was So Hated (And Cut From The Show)

Kaley Cuoco didn't play Penny in the unaired pilot of "The Big Bang Theory" — and audiences really didn't like Amanda Walsh, the actress who portrayed the show's original female lead, a character named Katie. 

In a 2022 interview with Entertainment Weekly commemorating the show's 15th anniversary, creators Bill Prady and Chuck Lorre looked back on the sitcom's rocky start. "In the first pilot, the female character is kind of rough," Prady revealed. "She's dangerous in a way and wasn't very nice to the guys."

"Yeah, the audience hated her," Lorre confirmed. Prady seconded that sentiment but then provided important context as to why the audience disliked Katie so much. It stemmed from how she treated two of the show's leads, Sheldon Cooper and Leonard Hofstadter (played by Jim Parsons and Johnny Galecki, respectively).

"We didn't realize early on that the audience viewed them as children. They were very naive and childlike, regardless of how intelligent they were. They were very vulnerable, and the audience didn't want a toxic presence around them," Lorre said. In the original pilot, the character of Katie is indeed more antagonistic toward the guys. While Sheldon and Leonard go on to have an almost sibling-like repertoire with Penny in the early seasons, the character of Katie has a harsh attitude and is quick with cutting insults. "That's why we rewrote Katie to become Penny and made her much more charmed by the guys and kind to them, as opposed to a woman who would take advantage of them."

Unfortunately for Amanda Walsh, audiences weren't fans of how mean she was to Leonard and Sheldon, so the pilot was reshot with Kaley Cuoco. The rest is history, but Chuck Lorre and Bill Prady believe they messed up with the original iteration of Penny and feel Walsh did a good job with what she was given to work with.

"She was terrific in the role, but the role was misconceived," Lorre confessed to EW. "It was our responsibility." Prady added, "Yeah, she was actually a very sweet person, and it was a lot of work for her to become that rough character."

Walsh had hoped to return to play the revamped Penny, but it didn't work out. "She had been so identified as that first character that it wasn't able to happen," Prady shared. Cuoco was cast instead, and the version of Penny she crafted alongside Lorre, Prady, and their writers was pivotal to the show's success.

Thanks to Kaley Cuoco's outstanding performance, Penny became an invaluable addition to "The Big Bang Theory." What's particularly striking is that the character's two closest relationships are with Sheldon and Leonard. After Leonard falls for Penny, the two share the typical sitcom "will they, won't they" dynamic for the first five seasons before embarking on a real relationship. Not only do Penny and Leonard get married twice (an elopement in Las Vegas followed by a wedding with the whole gang), but the series finale reveals that they're expecting a baby (fulfilling Leonard's prediction in the pilot that their children will be "beautiful and smart").

However, Penny's friendship with Sheldon might be even more important to the show's overall success. Though they couldn't be more different — and though Sheldon spends a frankly inordinate amount of time insulting Penny's intelligence — he ultimately realizes that she fully understands and truly cares about him. From the time Sheldon brings Penny to the hospital when she dislocates her shoulder to Sheldon's birthday party (where Penny is the only person who can help him as he hides in the bathroom), the two are undeniably close, and it's all due to Penny's inherently kind, sweet spirit.