This is the real reason why Kaley Cuoco almost wasn’t cast in The Big Bang Theory

It’s almost impossible to imagine The Big Bang Theory without Kaley Cuoco. The actress is as synonymous with that show as jelly is to peanut butter, but in a new interview with TV Insider, Cuoco said she originally struggled to land the part of Penny because she was too young.

Hardcore fans of the CBS series know that before Cuoco was cast, The Big Bang Theory shot a pilot with a different love interest named Katie, played by actress Amanda Walsh. That character was a drunk, angry trainwreck—a far cry from Cuoco’s Penny.

"In the first pilot, the character of Penny [originally named Katie] was not as appealing as that proverbial girl next door. It was not the actress [Amanda Walsh] but rather the conceit of the character," Peter Roth, president at Warner Bros. Television Group, told TV Insider. "Fortunately, Nina Tassler, then-president of CBS Entertainment, realized we had something very special and said, ‘Let's do it again.'"

They reconfigured the character as a flighty and lovable aspiring actress named Penny and brought Cuoco back in to audition after she failed to land the original role of Katie.

"I didn't get [the role of Katie] the first time around. I was too young, which I love saying because I don't get to say that I'm too young anymore," she told TV Insider with a laugh. "Then, a year later, I heard they were doing it again, and they brought me back in to read for Penny."

In case you were curious, here’s a scene from that original pilot with the proto-Penny character:

In the same TV Insider interview, Johnny Galecki remembers reshooting the pilot with Cuoco.

"It felt very natural, almost musical, [to reshoot] the pilot when Kaley was on board with Simon and Kunal," Galecki said. "It felt like a band you'd been playing with for years. And everything that everyone did complemented what someone else had to do. It was just fantastic. There's no recipe for that kind of chemistry."

The final episode of The Big Bang Theory will air on CBS on May 16th, 2019.