Kaley Cuoco stars as Penny, Sheldon and Leonard's beautiful next door neighbor. Penny is an aspring actress that currently works at the local Cheesecake Factory.
Penny moved across the halls from the boys after her split from her boyfriend of four years, Kurt. She briefly dated Sheldon, but it did not work out due to her insecurity about her intelligence.
Sheldon: I'm a physicist. I have a working knowledge of the entire universe and everything it contains
Penny: Who's Radiohead?
Sheldon [after twitching for a minute]: I have a working knowledge of the important things
Penny: What?! A few thousand people listen to you talk about nerd stuff?
Wil Wheaton: Again, right in the ears, straight to the feelings.