Susan

Susan (last name unknown) is the of Penny and  of Wyatt. She also has two other, one named Randall and a second  named Lisa who is never seen. She lives with her outside of, Nebraska on their small  where they raised their three children.

She was the only mother of any members of the gang who hadn't been seen on the show until she finally appeared in the first episode of Season 10 "The Conjugal Conjecture", except for Stuart Bloom's mother who up to that point is only mentioned and Emily Sweeney's mother and Leslie Winkle's mother who both haven't been seen or mentioned.

Overview
In "The Maternal Capacitance", Penny tells Leonard's mother Beverly that Susan could've done something to stop Wyatt treating Penny like a boy, like she could've told him that Penny is a girl and that he should get over it, then Beverly asked Penny if she was willing to talk about her relationship with Wyatt and Susan.

In "The Flaming Spittoon Acquisition", Sheldon implies that she's fat (as well as in "The Pulled Groin Extrapolation" where he states he has seen of her and sarcastically encourages Penny to keep eating) and Penny reveals that her mother smoked  when she was  with her.

In "The Transporter Malfunction", Leonard and Sheldon told Penny they didn't want to open the Star Trek she had just bought them because once you open the box, it loses its value. Penny relied, "Yeah, yeah, my mom gave me the same about my . I gotta tell you, it was a lot more fun when I took it out and played with it."

In "The Status Quo Combustion" Penny calls her mother to tell her about her to Leonard. She denies that she is and agrees that it is a first for their.

In "The First Pitch Insufficiency", Amy wants to know when Penny and Leonard are getting. They haven't set a date and Penny wants to wait long enough to prove to her mother that she's not pregnant.

In "The Bachelor Party Corrosion", Penny tells her that she  with Leonard. Her mother was out with Penny's brother Randall who was celebrating being for one  and had received his 10th chip on account of being sober for a month. Her mother was going to make her son a little to commemorate the occasion.

In "The Conjugal Conjecture" Susan first appears in person where she visits California with her son and husband to attend Leonard and Penny's wedding redo and is worried about her son that has formerly been on parole and what Leonard's parents would think about them.

Personality
Susan is a neurotic and stressed out woman, all from having had to deal with her troubled son. She was also seen to be whiny, including when someone tells her something good, like when Wyatt tried to make the trip happy, she told him to quit it. She is shown to be very embarrassed by her family's shortcomings: her son's criminal record and jailing, Wyatt's drinking, and their overall humble existence as a farming family. Although she had previously met Leonard and likes him, she was uncomfortable about meeting his academic parents, not wanting them to think of her family as "white trash". She goes to great lengths to present them in the best possible light, including buying dental implants for her son.

Family

 * Father: Unnamed
 * Mother: Unnamed
 * Brother or Brother-in-law: Unnamed
 * Husband: Wyatt
 * Father-in-law: Unnamed
 * Mother-in-law: Unnamed
 * Son: Randall
 * Daughters: Penny Hofstadter, Lisa
 * Son-in-laws: Leonard Hofstadter, Unnamed
 * Grandson: Unnamed
 * Nephew: Unnamed
 * Great-Nephews: Neil, Jeffrey, Scott Hofstadter, William Hofstadter, Richard Hofstadter

Penny
Susan loves her daughter a lot, but it seems there has been a bit of tension between them.

Wyatt
Susan and Wyatt are obviously happily married and so they are a good couple. Although during Susan's first appearance, things are a bit tense between them about Randall's drug actions and his ending up in jail and she's not pleased that Wyatt isn't being strict enough about it.

Penny's Siblings
Susan's relationship with her other daughter, Penny's Lisa is not known but it's obvious she loves her very much.

Meanwhile, Susan's relationship with Penny's Randall is seen to be a bit tense since he has been ending up in and out of jail and Wyatt may not have been strict enough about that.

Leonard Hofstadter
Like her husband, Susan is very fond of Leonard. She sees him as the first smart boyfriend Penny has dated and looked very proud at the wedding redo. She was also happy to see him again and hugged him.

The rest of the gang
Susan never met any of Penny and Leonard's friends yet who are members of the gang until "The Conjugal Conjecture" where she was with them at Leonard and Penny's re-wedding, but didn't speak to anyone. However, during the ride to the airport, she said that they are just lovely, although Sheldon is a bit peculiar.

Trivia

 * Kaley Cuoco originally had stated that she would like to have play Penny's motherLisa_Kudrow_2.jpg; however, she was quite pleased working with her former character's mother from "".
 * When Penny talks to her mother about being mother she tells her mother that she is not pregnant which was a first for their family.
 * She had already met Leonard off-screen before her first appearance. This was hinted in "The Bachelor Party Corrosion" (S9E3) when Penny, Bernadette and Amy are discussing Penny waiting to tell her she got  to Leonard, Amy says "Well, it's kind of sad that they don't know. I mean, they love Leonard." referring to Wyatt and Susan. It has since been confirmed in her first appearance ("The Conjugal Conjecture" (S10E01)).
 * According to a July 2016 article on the TBBT page, actress Katey Sagal had been cast as Penny's mother, Susan, and would be seen in the Season 10 premiere. This was a  of sorts for Sagal and Cuoco, who played mother and daughter on the sitcom . Kaley had stated that Katey Sagal is her "TV mom".