'Taxi' alum Judd Hirsch will appear in the season nine finale and play Johnny Galecki's dad.
After nine seasons, CBS' The Big Bang Theory is poised to introduce Leonard's father.
Taxi alum Judd Hirsch has been tapped to guest star on the network's nerdy comedy, producers announced Wednesday at PaleyFest.
Hirsch will make his debut in the May 12 season nine finale.
The casting marks the first time that Leonard's father will be seen on the veteran comedy. Details about the character have yet to be fully flushed out as producers are still working on the script for the finale. Showrunner Steve Molaro told THR on the red carpet that the episode might feature a cliffhanger.
"We're all honored to be invited to this James Burrows tribute … and we all had the opportunity to meet these incredible casts Jimmy directed and I had the opportunity to meet Judd Hirsch," Galecki said. "I ran up to him and bombarded him with conversation that went on for a long time about what a fan I am. 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?"
Interjected Simon Helberg: "And he said no but Rhea Pearlman is available …"
Galecki said he then called producers and they were all big fans and the rest was history. Joked co-creator Chuck Lorre of the Taxi love-fest: "And Danny DeVito will be [Howard and Bernadette's] baby next year!"
As TV's most-watched comedy heads into the back half of its ninth season, the series continues to round out the core cast's families. Leonard's mother, Dr. Beverly Hofstadter, has been featured multiple times with Christine Baranski taking home the Emmy for her guest turn.
Still to be introduced are Howard's father and Penny's mother, among other parental characters.
For Hirsch, the role comes as he's guest starred this season on ABC's The Goldbergs, playing young Adam's grandfather. His Big Bang Theory casting reunites him with Warner Bros. Television, where he starred on ABC's short-lived drama Forever. Hirsch is repped by Atlas Talent Agency.