Johnny Galecki expects 'Big Bang Theory' to end in 2019

Gary Levin | USA TODAY

PASADENA, Calif. — TV's top comedy The Big Bang Theory is guaranteed to return next season, and so will its successful spinoff Young Sheldon, which CBS renewed Saturday.

But after that, it's looking like the end for the Pasadena scientists, star Johnny Galecki said at the Television Critics Association.

"The only manner in which the cast has discussed wrapping the show is that we're all going to be very sad when that day comes," he told USA TODAY. "But I think at this point, everyone's very comfortable with 12 seasons being the time to go home and see our families."

CBS would love to have the comedy go on indefinitely, but with top stars earning $1 million an episode the show has become expensive for the network and producer Warner Bros. (ABC's Modern Family is also expected to end in 2019). But stars often express reservations about returning as negotiating leverage, so it's possible the show could be extended beyond its current two-year deal.

Galecki appeared to promote midseason comedy Living Biblically, which he executive produces, that features his former Roseanne castmate Sara Gilbert in a recurring role.

And he explained why he appears in only one episode of ABC's upcoming Roseanne revival.

"It's a different network," Galecki said. "There were just some politics to be considerate about. If they come back next year, I would love to more."