The Big Bang Theory: Who Did Keith Carradine Play & Why Was He Important?

Throughout its 12-season run, "The Big Bang Theory" had no shortage of guest stars, and the actors who played the main characters' parents were among the most impressive. Laurie Metcalf played Sheldon's (Jim Parsons) mother, and the inimitable Judd Hirsch and Christine Baranski played Leonard's (Johnny Galecki) parents.

In Season 4, Episode 9, titled "The Boyfriend Complexity," Keith Carradine made his "Big Bang Theory" debut as Penny's (Kaley Cuoco) father, Wyatt. While her dad is visiting from Nebraska, Penny pretends she and Leonard have gotten back together to make him happy. "You're the first guy he's ever really approved of, you know?" she tells Leonard. "You're a scientist who went to college, and you don't have a neck tattoo, or outstanding warrants, or a baby."

Wyatt eventually catches wind of their ruse, but he continues to champion the couple's reunion. "I want grandkids before I die, and I want them to grow up in a house without wheels," he tells Leonard. It's hard to say if Wyatt directly impacts Penny and Leonard's eventual reconciliation, but his persistence couldn't have hurt.

Carradine ultimately appeared in five episodes of "The Big Bang Theory," often via phone calls with Penny. He's warm and affable with a taste for beer (the apple doesn't fall far, as they say) and also has a dry wit. At his daughter's wedding, he sagely discourages Leonard from lending money to his new brother-in-law.

David Carradine comes from a family of actors; his father, John, was a noted character actor, and his brother, David, was best known as the titular assassin in "Kill Bill." Carradine is famous for his performances in "Nashville," "Pretty Baby," and "Cowboys & Aliens," as well as the series "Dexter," "Fargo," and "Deadwood."

For fans of "The Big Bang Theory," Carradine was a welcome addition to the sitcom. "I love Keith Carradine as Penny's Dad, and I'm glad they revamped that character a bit," wrote u/MuggsyTheWonderdog on Reddit. "I like their father-daughter relationship." When Penny first mentions her dad in Season 2, she calls him Bob and implies they have a strained relationship. But by the time he materializes as Wyatt in Season 4, the pair is chummy, and he affectionately refers to her as "slugger." U/Satinsbestfriend concurred, writing on a separate subreddit, "Wyatt is probably my favorite recurring character."

Fans had love for Penny's entire family. In an eye-winking bit of casting, her mother was played by Katy Sagal — the same actress who previously played Cuoco's mother on "8 Simple Rules." Jack McBrayer appeared in one episode as Randall, her brother with a history of cooking meth. "I love Penny's family," another Redditor wrote. "They just seem so unaffected, warm, and funny. I get why Penny has such a big heart and emotional intelligence and strength."