Included among them are parents of the main characters, their dates and their coworkers.
Celebrities such as Stephen Hawking occasionally appear in cameo roles as themselves.
His disorder is confirmed by Amy in the ninth season.
Sheldon Lee Cooper (Jim Parsons) is a theoretical physicist, possessing a BS, MS, Ph D, a Sc. Originally from East Texas, he was a child prodigy, as he had received his Ph D at age 16.
He is usually cold, self-centered, condescending, and immature, but at the same time it is commonly not intentionally hurtful and is in a well-meaning way; He just doesn't know any better.
The two attempted a long-distance relationship after Priya moved back to India, but Leonard eventually broke up with her in season five after she admitted to cheating on him with her former boyfriend.
In season five's "The Recombination Hypothesis", Leonard and Penny start dating anew, and although their relationship is initially rocky and Penny has doubts, in season six, she works through her doubts and has a stronger relationship with Leonard.
A common joke is his inability to drive, relying on those around him to help him get anywhere.
Unlike Leonard and Raj, who come from intellectual families, Sheldon stands out from his own relatives.His commitment to his friends is often called into question, as he is known for constantly and consistently being condescending and rude, many times even without being intentionally hurtful.He also has difficulties lying or keeping a secret, giving himself away with wild facial tics and implausible statements.In season six's "The 43 Peculiarity", she tells him she loves him for the first time, and this now makes them more comfortable in their relationship.Over the next two years, they talk about marriage and each have unsuccessful proposals until the penultimate episode of season seven, when they become engaged, and finally get married in the ninth-season premiere, followed with a wedding redo for their friends and families since the couple had eloped.His father, George, whose death antedates the series, is described as a stereotypical Texan who liked football, skeet shooting, and heavy drinking; his mother, Mary, is a devout Evangelical Christian, who does not seem to understand her son's fields of study, although she does display common sense and intelligence; his fraternal twin sister, Missy, and as-yet unseen brother, George Jr., were both described by Mary as being "dumb as soup".