7 Actors Who Turned Down The Big Bang Theory

"The Big Bang Theory" was studded with famous guest and recurring stars. From Carrie Fisher appearing to yell at James Earl Jones for pranking her to Bill Nye the Science Guy engaging in a feud with another big children's science show hosting celeb — Bob Newhart's Professor Proton — the show sprinkled in its geeky guests with a sense of humor and aplomb. Wil Wheaton even manages to become Sheldon's nemesis over multiple seasons, making him one of the best "The Big Bang Theory" secondary characters. 

While the comedy was such a huge hit that one can't imagine anyone ever saying no to doing it, instead of unlocking their inner nerd, some stars did reject regular parts, recurring appearences on the series, or guest-starring roles. The reasons for these rejections are myriad, but sometimes it led to the actor appearing on the show in another capacity. Here's a roll call of all the celebrities who said "no" to popping up on "The Big Bang Theory." 

William Shatner is well-known for his irascible ways and his desire to keep a strong hold on his own reputation, so it's not surprising that he turned down Sheldon and his bros the first time they asked him for a cameo. Why did he reject a guest spot on "The Big Bang Theory" playing himself at first?

"I've had several conversations with the creators, and what they wanted me to do, didn't seem to be exactly right, so I said 'find something that's better'. They may have taken umbrage at that, I'm not sure. They wanted me to play myself a little obliquely, and they said it would work out, but I needed more assurance on that," he told Digital Spy about being asked to be on the comedy in 2016. 

Since Shatner is a longtime director and guardian of his own public image, he's always had a bit of an iron grip on how the public sees him. So it's probably no big surprise he rejected the appearance to do other things — but in the end it all worked out, and he popped in "The D&D Vortex" during Season 12. He's a part of Wil Wheaton's star-studded D&D team, which also includes Kareem Abdul-Jabbar. 

A number of now-famous actors got a shot at leading "The Big Bang Theory," including Brie Larson, who almost played Penny. But the most interesting main casting miss is that of Macaulay Culkin, who just flat-out turned down being cast on "The Big Bang Theory" three times in the role of Leonard Hofstadter. When the show was casting, producers came on a little too strong to get him on board. Not that wild about starring on sitcoms in the first place, he said on the Joe Rogan Experience Podcast that the show's producers never attracted his approval. "They pursued me for The Big Bang Theory. And I said, 'no,'  [...] the pitch was, 'Alright, these, like, two astrophysicist nerds and then a pretty girl lives with them — yoinks!' That was the pitch [...] I said, 'Yeah, no, I'm cool, thanks.'" 

CBS kept trying to beg the actor into appearing, though he was clearly disinterested. "They came back at me again, and I said, 'No, no, no. Again, flattered, but, like, no.' Then they came back at me again, and even my manager was like twisting my arm." But Culkin stayed firm on the topic, and eventually the hunt moved elsewhere, with Johnny Galecki making big bucks in the role. When asked if he regrets skipping a trip to Pasadena, Culkin said, "I'd have hundreds of millions of dollars right now if I did that gig. At the same time, I'd be bashing my head against the wall." A wise reason to say no to anything.

Harrison Ford is another fondly irascible science fiction legend who got a chance to cameo on "The Big Bang Theory" but turned the show down. Per an interview given by executive producers Steve Holland and Steven Molaro to Yahoo Entertainment Suite at San Diego Comic-Con in 2018, they wanted Ford, but casting director Nikki Valko later revealed in the book "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series" that they couldn't charm the actor into saying yes.

"We would have loved Harrison Ford, but that never got any traction. He just was not open to it," Valko explained. Harrison Ford, of course, has always had a laconic sense of humor about his participation in the "Star Wars" universe, with the slightest touch of crankiness — after all, he's always wanted Han Solo to die. Even though James Earl Jones, Mark Hamill and Carrie Fisher made guest-starring appearences on the show, it's understandable why he might not have wanted to be a part of the festivities. 

Plenty of lovely ladies passed through Sheldon and Leonard's apartment over the years, but one face never made it to the big dance, even though she likes the series. Selena Gomez admitted in an Instagram post that she loves "The Big Bang Theory," but couldn't make it onto the show in spite of the producer's enthusiasm. While she was approached more than once to be on the program, it never worked out due to scheduling conflicts.

The show even had an idea for her guest role. "I had kicked around an idea that Amy [Farrah Fowler] had been complaining about her awful stepsister," executive producer Steve Molaro revealed in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series" (as reported by TVInsider). But when the sister visits, it turns out she's sweet as pie — naturally leading to her becoming popular with Amy's friends and extended family. Unfortunately, fans will never get to see them go to war. 

He may have gotten by with a little help from his friends, but Ringo Starr himself turned down the chance to help out some geeky friends on "The Big Bang Theory" by appearing as one of the main character's fathers. The character in question turned out to be Howard Wolowitz (Simon Helbig), whose image and facial features drew comparisons to a young Starr's. Executive producer and series creator Chuck Lorre thought the resemblance was so credible, he encouraged the show's casting agent to try to make contact with The Beatles superstar.

"You could buy the genetic link to Richard Starkey ... We pursued it to the point where we got a solid no [from Starr and his people]," he explained in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series" (as reported by TVInsider). But with Starr's team rejecting the idea, they had no choice but to scrap the whole idea. Howard's father has remained distant and absent ever since.

Another actor who turned down "The Big Bang Theory" when it was in its nascent days is former "House" star Kal Penn. Speaking on The Covino & Rich Show, Penn revealed that he'd been sent a script and wasn't sure it was right for him at the time. "Oh, I don't know, this is kind of stereotypical," he admitted, adding that he didn't want to play an exchange student after being in Van Wilder. But he was also doing movies and didn't know if he wanted to anchor himself to a TV show. Turning it down meant the role went elsewhere.

Penn seems to be completely fine with having missed out on all 11 seasons of mayhem the sitcom offered, even as the show's script evolved to make the characters full-fledged adults. But, unlike others who turned down the CBS sitcom, Penn eventually guest starred on "The Big Bang Theory" multiple times as Dr. Kevin Campbell. Per what he said on The Covino & Rich Show, he had a good time. He added that Kunal Nayyar, who ended up playing Raj Koothrappali, did a much better job in the role than he could have. 

Lastly, another major Hollywood starlet rejected a cameo on the series – movie star Sandra Bullock. The show hoped to get her on board for its series finale after spending years establishing Raj Koothrappali's crush on the actress. The plan was to have her cameo during the Nobel Prize ceremony when Amy and Sheldon win their awards. Unfortunately, scheduling mishaps got between the producer's plans and Sarah Michelle Gellar was tapped to appear as Raj's date instead.

"Sandra Bullock was actually our first go-to because of Koothrappali's long love of her. We were really excited about it, but we got a polite decline because she was shooting a movie and wasn't available," Executive Producer Steve Holland said in "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series" (as reported by TVInsider). But, he noted, they were all happy and excited to work with Geller, leading to a joyous ending for one and all.