The Story Behind How CBS Hated The Big Bang Theory’s Original Penny And How Kaley Cuoco Became The ‘Secret Sauce’

 Kaley Cuoco as Penny in The Big Bang Theory.
Kaley Cuoco as Penny in The Big Bang Theory.

There’s arguably been no unaired series pilot more legendary in recent years than the original one for CBS' The Big Bang Theory pilot. That early episode has been referred to as “just a mess” by series creator Chuck Lorre due to the original script and some of the cast, particularly the original Penny actress. The network has made it no secret just how much it disliked the original star that served as the precursor to Kaley Cuoco, who has since been referred to as the show’s "secret sauce."

The network’s not-so-secret hate for the original Penny (who was actually named Katie) is just one of several interesting behind-the-scenes secrets about Big Bang. Former CBS Entertainment chairwoman Nina Tassler opened up to Emmy Magazine (via The Direct) about watching the original pilot. The veteran executive mentioned that the script had elements that worked and some that didn't. Tassler alluded to original Penny actress Amanda Walsh being the weak link in the original episode, commenting:

There was so much about the pilot that did work. But there were parts of the script that didn't work, and we had to recast an actress. [Chuck Lorre] is such an extraordinary talent. He had a great concept and wonderful chemistry between the two leads, so I asked him if he would try again.

At least, the Eye Network knew it had something special in the classic sitcom and gave the producers and his collaborators another crack at it. The original TBBT pilot went unreleased for a while but leaked online years ago. If you've seen it, you might agree that Nina Tassler’s notes were right! Some elements worked, while other elements needed to be tossed or redeveloped. The original characterizations of Leonard, Sheldon, and Penny’s predecessor Katie were off-putting, to say the least. So, because CBS executives realized the show was an unpolished gem, fans received the pop culture-dominating sitcom we know today.

It seems evident that while Nina Tassler loved John Galecki and Jim Parsons' chemistry and performances, not much could be said about Amanda Walsh. Tassler mentioned that Chuck Lorre agreed with her assessment and went ahead to rewrite and recast Katie's role as Penny. The TV exec saw the series going far after seeing the newly-cast Kaley Cuoco in the revamped pilot, per Tassler:

And he immediately said, to his credit, 'You're right, I know I can do better. Thank you for this opportunity, and we'll figure it out.' Sure enough, he did. Kaley Cuoco joined the cast, and she was the secret sauce. Chuck and Bill Prady delivered a pilot script, and the rest is history.

More on The Big Bang Theory

Kaley Cuoco in The Big Bang Theory.
Kaley Cuoco in The Big Bang Theory.

The Big Bang Theory Had Three Surprising Actresses Vying For Lead Role Over Kaley Cuoco

Boy did the revamped TBBT pilot make history. The Big Bang Theory went on to become the highest-rated sitcom on TV for years, staying in the Top 10 for its final eight seasons. The show and the cast were nominated and collected many awards, including a few Primetime Emmys for Jim Parsons. Ultimately, the CBS sitcom ended its 12-season run in 2019 after Parsons chose to move on to other projects. It seems like Kaley Cuoco was the missing puzzle piece and helped Penny gradually evolve. One would think that fans are happy that things turned out as they did.

While fans hold out hope for a Big Bang Theory reunion or revival someday, the universe is still alive through the spinoff series Young Sheldon, which itself will end after seven seasons. They can revisit the original series by streaming it using a Max subscription. After reminiscing over the classic sitcom, you can look over our 2024 TV schedule to see when your favorite comedies will premiere this year.