Big What If Theory

As with most of our most beloved shows, once we get attached to the characters and the stars that play them, it's almost impossible to imagine anyone else in those roles. But, with The Big Bang Theory—as is often the case—the cast we got could've been kind of different had other choices been made. These are some of the other casting options that were considered.

Sheldon: Johnny Galecki

Johnny Galecki was the only cast member that Chuck Lorre knew he wanted right from the beginning. However, his initial thoughts were to have Galecki playing the Sheldon role. It was actually Johnny himself who made the call and requested he take on the Leonard role. As he later explained it to Variety: "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".

Gage Skidmore, CC BY-SA 2.0, Wikimedia Commons

Macaulay Culkin

Culkin told Joe Rogan that he was asked to audition for the series on more than one occasion, but he turned them down every time as it didn't seem like something that would interest him. Some reports state that the role they wanted him for was Leonard while others just say it would've been some main character.

zuko1312, Flicker

Howard's Mom: Pamela Adlon

As most TBBT fans know, Howard's mom passed away on the show because the actress who played her, Carol Ann Susi, sadly passed on in real life. However, after Susi died, it wasn't an automatic choice to have the character pass as well. There was some consideration given to possibly having actress Pamela Adlon take over the role (well, the voice—since you never actually saw his mom for more than a brief second anyway).

They decided not to go that direction but, fun fact: It was Adlon who voiced the Wolowitz's crying baby Halley in the hospital nursery scene.

Sebastian Jespersen, CC BY 2.0, Wikimedia Commons

Amy Farrah Fowler: Kate Micucci

Could Sheldon have ended up with Lucy? Well, no. But Katie Micucci—who ended up playing Raj's socially awkward girlfriend, Lucy—did originally audition for the role of Amy Farrah Fowler. While the producers went with Mayim Bialik instead, they did remember Micucci when the Lucy role came around.

Genevieve, CC BY 2.0, Wikimedia Commons

Leonard: John Ross Bowie

Barry Kripke, the guys' nemesis at the university, is played brilliantly by actor John Ross Bowie. However, before auditioning for that part, Bowie had two auditions for the role of Leonard.

Gage Skidmore, CC BY-SA 2.0, Wikimedia Commons

Katie: Amanda Walsh

"Who is Katie," you ask? Well, she was the "Penny" role in the first pilot they filmed for the series. However, that pilot didn't test well—and neither did the Katie character. So, after some re-working and re-writing they tried again, this time with a "Penny" instead of a "Katie", and Walsh was out.

Tibrina Hobson, Getty Images

Sheldon: Kevin Sussman

We aren't sure how close he got, but Sussman wanted the Sheldon part and auditioned for it. Instead, he became Stuart—but not before auditioning for another main character.

Gage Skidmore, CC BY-SA 2.0, Wikimedia Commons

Howard: Kevin Sussman

Turns out Sussman also auditioned for the Howard role as well.

Robert Williams, Flickr

Penny?: Brie Larson

In a video she uploaded to her YouTube channel in 2020, Brie Larson discussed some of the parts she auditioned for over the years and didn't get. One of which was for a character on The Big Bang Theory. She doesn't say what the part was that she auditioned for, but most people assume it was Penny.

Fariha Janam, Flickr