Penny mentioned his father at least twice before he appears in the show.
According to Penny in "The Maternal Capacitance" (S2E15), Wyatt originally wanted a boy, but got her instead. He called her "slugger" until she got her first training bra, at which point he also stopped playing catch with her.
In "The Maternal Congruence" (S3E11), Penny mentions that Wyatt sent her a catcher's glove and a baseball for Christmas. When he learned that Penny was seeing Leonard, he was overjoyed, having met her ex-boyfriends. He was actually devastated at learning that they had broken up.
In "The Boyfriend Complexity" (S4E09), Wyatt is first seen in person. He comes to visit Penny, who claims, in order to get him off her back, that she and Leonard have got back together. As the episode progresses, the two carry on the ruse until Penny admits the truth to him. He is at first hurt that she felt a need to lie to him, but forgives her. When she is gone, Wyatt literally begs Leonard not to give up on her, as he is the best boyfriend she's ever had. He pretends to angrily throw Leonard out of the apartment as reverse psychology to get Penny's interest in him up. Leonard leaves, telling Wyatt that he will Friend him on Facebook.
In "The Hesitation Ramification" (S7E12), Penny has a phone call with her father after it is found that her role in NCIS is cut when aired. Penny tells Wyatt that her part wasn't cut because she was too pretty. He also doesn't need to come to Los Angeles to kick Mark Harmon's ass. Wyatt does not appear on screen in this episode, nor is he heard.
- The first mention of Penny's father was in "The Maternal Capacitance", where she called him 'Bob'. However, his name was later changed to Wyatt.
- Wyatt's last name is unknown, since the last name of his daughter Penny has yet to be established.
- He is one of three fathers of the main cast who has physically appeared on the show; the others being Raj and Bernadette (Leonard's father is only mentioned, Sheldon's is dead, Howard's left him at 11, Amy's has neither been seen nor mentioned and Stuart's is only mentioned)