Although starting out on a low-key note, “The Big Bang Theory” soon exploded in popularity thanks to its canny mix of humor and references to geek pop culture that general audiences could also enjoy. By its middle seasons the show was highly successful, with fans among audiences and celebrities alike.
It soon became a badge of honor for celebrities to appear on “The Big Bang Theory,” especially those connected to geek culture. Take, for instance, former “Star Trek: The Next Generation” star Wil Wheaton, who ended up playing a version of himself across several episodes as Sheldon’s long-term nemesis. Or Mark Hamill, who was preceded by fellow “Star Wars” actors Carrie Fisher and James Earl Jones (via Cinema Blend).
It wasn’t just actors getting in on the action. “The Big Bang Theory” also proved a hit with the scientific and technical crowds, and people like Elon Musk and Neil deGrasse Tyson have played versions of themselves in various episodes. However, perhaps the most iconic appearance was the one made by renowned physicist Stephen Hawking. It was this particular cameo, more than any other, that Jim Parsons found nerve-wracking to film. “It was an intimidating [experience],” the actor told CBS News. “I’d be lying if I said I was comfortable. … To get to finally meet him was, it was just overwhelming.”