“The Big Bang Theory” is introducing Leonard’s (Johnny Galecki) dad! But, wait — hasn’t the hit CBS sitcom featured the Hofstadter patriarch before? Viewers have met Leonard’s strict mother, Dr. Beverly Hofstadter (Christine Baranski), but his father has previously only been mentioned!

The cast and creators of “The Big Bang Theory” took the stage at PaleyFest in Los Angeles Wednesday to talk about the remaining episodes in Season 9. It was there that they announced that “Taxi” alum Judd Hirsch will be joining the cast in the May 12 finale as Leonard’s father, Dr. Hofstadter.

Details regarding Hirsch’s plotline have yet to be revealed, but Galecki did tease that the casting kind of came out of NBC’s tribute to director James Burrows in late January.

“I ran up to [Judd Hirsch] and bombarded him with conversation that went on for a long time about what a fan I am,” Galecki explained to the PaleyFest audience. “I did share with him that when we were shooting the pilot, I rewatched the first two or three seasons of ‘Taxi’ — not because I wanted to base Leonard on his character but the purpose his character served — this anchor in this group of people — and he was just as much at times a voice of reason as he was just as confused as everyone else. I shared that with him and a lightning bolt struck … or another merlot … and I said, would you have any interest in playing my dad on the show?”

So far the only details that fans have regarding Leonard’s father come from comments he made about him in passing. Like Leonard and Beverly, Papa Hofstadter also has a PhD, but his area of study is anthropology. He’s divorced from Leonard’s mother, however, it’s unclear when it happened or why. It’s easy for viewers to assume that the split had something to do with lack of affection from his wife. Beverly is a psychiatrist who doesn’t believe in coddling or showering people with love. As a child Leonard actually built a robot to give him hugs. He joked that his dad ended up using it as well. 

According to the Hollywood Reporter, the writers are still working on the script, but showrunner Steve Molaro teased that the episode might feature a cliffhanger.

“The Big Bang Theory” Season 9 finale will air on CBS on May 12. Fingers crossed he’s easy going and laid back like Penny’s dad!