The Big Bang Theory Star Who Almost Played Sheldon Cooper Before Jim Parsons

It's almost hard to imagine anybody besides Jim Parsons playing Sheldon Cooper on "The Big Bang Theory." For 12 years and seasons, Parsons perfectly crafted the lead character of Sheldon — a brilliant yet irascible theoretical physicist who lives with his best friend Leonard Hofstadter (played by Johnny Galecki). As it turns out, Galecki almost played Sheldon ... but then asked showrunner and creator Chuck Lorre if he could be considered for the role of Leonard instead.

As Galecki told Variety in 2015, he felt like he understood Leonard better than he understood the character of Sheldon — and he also wanted to pursue Leonard's storyline, in which the experimental physicist falls for and subsequently woos his gorgeous new neighbor Penny (Kaley Cuoco). As the "Roseanne" alum put it, he'd rarely gotten the opportunity to play a romantic lead yet in his career, and he was too tempted by Leonard's immediate crush on Penny. (The pair date on and off and eventually get married.)

"It was a very selfish request on my part," Galecki explained. "I hadn't been able to traverse those stories of the heart. I've often been cast as the best friend or the gay assistant of whatever character got to explore those relationships. I said I'd rather play this guy, who seems to have a future of romantic triumphs and difficulties."

Johnny Galecki actually expanded on this whole thing in Jessica Radloff's 2022 book "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series" — and said he made the process pretty difficult for Chuck Lorre and Lorre's co-creator Bill Prady. "I was usually cast as a character's comic relief best friend or gay assistant, so I was riding pretty high on my ego in this role," Galecki recalled to Radloff. "But then, the more material I got from Chuck and Bill, the more I was drawn to the Leonard role, especially since it seemed like Leonard might have a better chance at romantic relationships on the show. I thought they would say, 'Go f*** yourself, end of conversation,' but Chuck just said, 'Well, great, play that guy.'" Even after that, Galecki called himself a "difficult piece of casting," because he kept saying no to the show.

As Galecki revealed, he doubted whether or not the show would even take off — and he wanted to stay onstage in New York and not waste his time on a show that might not even succeed. "My longtime agent said, 'Why do you keep turning this down? Are you afraid that it's going to get picked up to series and then you'll have to sign another seven-year contract and not be able to go back to New York full-time?' And I said, 'No, I don't know if it's going to get picked up or be successful,'" Galecki said. Apparently, his agent got him to change his mind ... but still, Galecki certainly didn't make things easy for Lorre and Prady. "And I can confess this now because it only illustrates what an idiot I am, but I did turn down the role five times before eventually saying yes," the actor admitted.

Apparently, it wouldn't have mattered if Johnny Galecki did want to play Sheldon — because everyone who saw Jim Parsons audition for the character realized he was beyond perfect for the part. As casting director Nikki Valko noted in Jessica Radloff's book, "It wasn't like he came in with a bow tie or looked real nerdy. But boy, when he opened his mouth I couldn't believe what came out of it, just all that science. As far as Ken [Miller, my fellow casting director] and I were concerned, once Jim read for Sheldon, we knew. He just understood the character from day one."

Chuck Lorre also confirmed this in the book, saying that Parsons seemed to innately understand Sheldon. "He didn't just come in and read the lines," Lorre recalled. "He had prepared a fully realized character. He had prepared the material so his dialogue had a rhythm, intonation, syntax, the pauses, everything was calculated. He had decided how this character handles his body, how he occupies space, or is uncomfortable occupying space. It was a whole other level of audition. And it was not the character that I envisioned. Frankly, I don't remember what kind of character I envisioned, but that wasn't it! I was thrown off in a good way. Ken, Nikki, Bill, and I were laughing our asses off."

Bill Prady said that Parsons' audition was so good that it actually led to some doubts, but they were unfounded: "I said, 'I need to see it again.' I wanted to know if he could create that performance again. And he did it perfectly, as if he had never done it before. This is why the man's got like 19 Emmys."

Fortunately, everything worked out — and after the creative team behind "The Big Bang Theory" decided they wanted Johnny Galecki and Jim Parsons to play Leonard and Sheldon, they brought the two together for a chemistry read. The rest, as they say, is history.

"These characters are supposed to be an odd couple and see the world differently from each other. There was an innate tension there, and that was the chemistry," Parsons recalled in Radloff's book, saying that after reading with other options for Leonard, he realized Galecki was just the exact right fit. "I read with so many different Leonards at the start of this process, but the second I read with Johnny, I was like, That's who it is. And it wasn't because he was a 'good' Leonard, or the way he was saying his lines, although I'm sure that was part of it, but it was just a feeling. We were able to be these two orbs that bumped up against each other. It was very freeing to me, which made the scene come alive."

For his part, Galecki agreed, and was apparently quite impressed with Parsons' strong understanding of Sheldon right out of the gate ... to the point where he felt proven right in choosing to play Leonard. "Jim was so honest and unique and driven," Galecki said. "He knew the result that he wanted from his performance, which is very different from just performing and inhabiting a character. And as soon as I saw him doing what his take on Sheldon was, I was immediately proud of myself for having the intuition that I should not have done that character."

"The Big Bang Theory" is currently streaming in its entirety on Max.