Originally from Omaha, Nebraska, Penny is a waitress at the local Cheesecake Factory with aspirations of becoming an actress. In contrast to the rest of the group, Penny is not particularly intellectually gifted or savvy in a specific technical field, but she has great social skills and is very knowledgeable about pop culture. Penny is messy and disorganized, but appears to like it that way. She also has full confidence in horoscopes and often has arguments with Sheldon and Leonard about their accuracy.

For the most part, Penny cannot stand Leonard’s roommate Sheldon Cooper, and the two of them have clashed several times. Jim Parsons described the characters as ”polar opposites”.

In one episode, Sheldon tries to ”improve” Penny using chocolate, rewarding her for what he considers to be ”correct behavior”, as in operant conditioning with lab rats. As Sheldon observed, Penny will often call someone ”sweetie” coupled with a thinly-veiled insult.

Despite this, at times Penny and Sheldon have shown to be good friends; Penny took care of Sheldon while he was ill and let him stay at her apartment when he was locked out of his; Sheldon lent money to Penny when she needed it and took care of her when she dislocated her shoulder. During a Christmas episode, Penny gave Sheldon a signed napkin used by Leonard Nimoy. In return, Sheldon gave Penny multiple baskets of bath products and then a long hug, to both her and Leonard’s surprise.

It was in the second season finale that Penny finally showed strong romantic feelings for Leonard. When she discovered that Leonard and the other guys would be spending three months at the North Pole for a scientific experiment, she became sad and gave him a Snuggie and an unusually long hug, which Leonard described as lasting for ”five Mississippis”. In the third season premiere, after the guys returned from the expedition, Penny kissed Leonard right when he arrived at her door. Subsequently, Leonard and Penny finally made love for the first time.

Penny’s last name has not been revealed, though co-creator Bill Prady stated that it eventually will be.