'Big Bang Theory' Almost Starred Completely Different Actress Instead of Kaley Cuoco

The Big Bang Theory almost starred a completely different actress, instead of Kaley Cuoco, for the role of Penny, and fans are going to be very surprised at who nearly won the part. The Hollywood Reporter has shared an exclusive excerpt of The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series, a new book that details the oral history of the hit Chuck Lorre-created CBS sitcom. In the book, it is revealed that Marisa Tomei was previously considered for the role that eventually went to Cuoco.

"I had the part of Sheldon for a long time before everything was settled. I read with Marisa Tomei," Big Bang Theory star Jim Parsons says in the book. "Johnny was cast by then, but he was doing a play in New York. I had come back to read with her. I remember going to the snack room after we were done and telling Ken and Nikki [Valko, casting director], 'I've never been in someone else's audition before!' And they said, 'Well, she was kind of really auditioning you.' And I went, 'Oh, that makes sense.' But oh my gosh what a different world that would have been."

Notably, Tomei would not have been playing Penny as fans came to know and love her. She was auditioning for Katie, a character who eventually was evolved into Penny. In a description of the roles, The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series author Jessica Radloff says, "The character of Katie was nothing like the character of Penny that audiences would come to know and love. Penny was bubbly with a Midwestern innocence and optimism; Katie was cynical, down on her luck, and off-putting." Bill Prady, series co-creator, added, "Tara Reid also came in for the role of Katie, and I think Elizabeth Berkley went to network for the role, too. She was terrific."

When it comes to how Cuoco ended up landing the role of Penny, casting director Ken Miller recalled, "Kaley Cuoco went to the network and tested for the first pilot of Big Bang. She's so sunny and bubbly, and they just loved her, but she just didn't bring the dark qualities. She just wasn't the essence of Penny in that first incarnation." Cuoco added, "I loved the role, and I loved Chuck. I had worked with him when I was fourteen or fifteen on a pilot called Nathan's Choice. I know Chuck really wanted me for the role of Katie, and I was definitely bummed when I didn't get it, but I kind of have a way of moving on because you have to."