Will there be a 'Big Bang Theory' prequel spin-off?

“The Big Bang Theory” character Sheldon Cooper may be coming to a new CBS sitcom as “Big” reaches double-digit seasons. 

CBS is reportedly working on a spin-off to “Big” that would center on Sheldon when he is younger. The sitcom would thus be a prequel to “Big” and a new actor, not Emmy Award-winning actor Jim Parsons, would portray Sheldon.  

Mr. Parsons would reportedly serve as an executive producer on the project and “The Big Bang Theory” co-creators Chuck Lorre and Bill Prady would be behind this show as well. 

“Big” is currently airing its 10th season and ranked as the most-watched comedy of the 2015-2016 TV season among total viewers and viewers 18-49. 

For many shows, entering those double digits seems to be when programs either go off the air or change in some way. Such hit shows as “Friends” and “CSI: Miami” ended after 10 seasons, while other hit programs including “M*A*S*H,” “Frasier,” and “Cheers” all concluded after 11.

For some shows, they may not have been as relevant in pop culture by the time they ended. Flavorwire writer Jillian Mapes wrote of “Frasier” near the end of its run, “The show’s worldview started to feel out of place in an increasingly digital, culturally segmented world.” 

And actors may be finished the show when it’s been on for so long. “Cheers” actress Rhea Perlman remembered in an interview with the Huffington Post, “I think where we all drew the line was when Ted [Danson] wanted to leave. That seemed like, ‘No, this is the end.’ And we were all ready at that time. It was 11 years. But yeah, it just seemed like if Ted leaves, that’s the heart of the show. That’s not possible. You can’t go on from there.” 

Some of these long-running shows have attempted to capture the magic elsewhere, with “Friends” leading to “Joey” and “Cheers” leading to “Frasier.” “Frasier” was of course hugely successful, but “Friends” co-creator David Crane, who was not involved with “Joey,” noted in an interview with Entertainment Weekly, “There are very few examples in television history of a spin-off that works. It’s very difficult. As talented as everyone is, I think it’s a really tall order. And also, the audience expectations are unreasonable.”

Those at CBS are taking a somewhat unusual path for the planned “Big” spin-off, as many spin-offs have characters moving on from the show rather than viewers seeing them before the program started. One exception is AMC’s Emmy-nominated program “Better Call Saul,” which imagines character Saul Goodman before viewers met him in the highly acclaimed AMC program “Breaking Bad.”

More often, a spin-off has characters going on to new adventures, as when Joey Tribbiani moved to California or when Frasier Crane departed for Seattle.