The Big Bang Theory: 10 Best Characters Who Only Appeared In One Episode
4. Christy (Brooke D'Orsay)
Episode: "The Dumpling Paradox" (Season 1, Episode 7)
In this episode, Penny's promiscuous friend Christy has come to visit and the desperate Howard leaps at the opportunity to ask her out. While he's successful in alluring Christy, her expensive tastes and inability to get along with his mother proves to be problematic.
This was really the first episode of The Big Bang Theory to give us a female character who's as colourful and scene-stealing as Sheldon, Leonard, Raj and Howard. Female characters up until this episode had been largely generic and just used to accentuate the awkwardness of the four key men. Not so with Christy. She lights up the screen with fun and offbeat energy and yet she's able to hold her own when furiously arguing with Howard's mother - few other characters could say the same.
It's also hilarious to see Howard in ecstatic boyfriend-mode, and Christy deserves credit for bringing that out in him. That version of Howard would vanish in later seasons when he marries and has children.