Penelope "Penny" (surname currently unknown) is The Big Bang Theory's main female protagonist. She lives in apartment 4B across the hall from her boyfriend Leonard Hofstadter and Sheldon Cooper, his roommate and friend.
An aspiring but unsuccessful actress, she was born in Omaha, Nebraska and works at The Cheesecake Factory as a waitress. Penny is one of the main female characters in the show alongside Bernaddete Rostenkowski and Amy Farrah Fowler, as well as the first of the three to appear on the show.
She has been Leonard's love interest for most of the show, with the two dating briefly in the first episode of the second season, for most of the third season, and they rekindle their romance in Season 5's The Recombination Hypothesis. Despite their rocky on-and-off relationship, Leonard and Penny are good friends, and she gradually becomes part of the guys' social group.