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Katie was the pre-Penny female lead in the Unaired Pilot of The Big Bang Theory produced for the 2006-2007 television season. Katie was played by actress Amanda Walsh, "a street-hardened, tough-as-nails woman with a vulnerable interior". She works at the cosmetics counter of a local department store.


Kate is found by Sheldon and Leonard on the curb crying and left homeless by her former boyfriend. Leonard, despite Sheldon's objections, invites her to dinner and then to stay a few days at their apartment. She is abrasive, sexy, hard, and sarcastic, but she softens a little when she discovers that the guys aren't trying to get something from her. In the end, she decides she'll crash at their place for a while.

Katie meets their geeky friend Gilda, an early Leslie Winkle prototype, who likes Leonard and is jealous of her until Katie says that she had no romantic interest in the two nerds.

Katie goes out drinking and arrives back at the apartment late at night, waking Leonard by smashing a lamp. Katie starts ranting to Leonard about her life and why it sucks, using the whiteboard, drawing colorful diagrams to explain her point. Leonard points out that her problems weren't caused by her mother, boyfriend etc., but by her making stupid decisions. Katie misguidedly assumes that Leonard is calling her "stupid" (even though he is not) and as a result, she gets offended and moves out.

The next morning while Katie is serving a customer in the department store, Leonard comes to apologize, even though he had nothing to apologize for and to do so would only have given her a free pass on her behavior. Katie later takes her things back to their apartment and says that staying there is her only rent-free choice. She then takes Leonard, Sheldon and Gilda out dancing.

Audience Reaction[]

The audience did not like the way Katie was mean and mocking Sheldon and Leonard, so she was dropped for the second pilot and replaced by Penny who is sweet and caring. Penny does exhibit some of these mean and mocking traits in some later episodes (as well as making misguided assumptions about what someone may say and twisting the other person's words out of context, as Katie did in the pilot) when she gets really mad at people. She apologizes when she offends someone.


  • Mother: Barbara
  • Stepfather: Henry


  • She was the supposed to play the main antagonist in the series, where she is the mean girl of the show and picks on the geeks on the show. She was replaced by Penny, where she is the sweet and nice girl who hangs out with Leonard.
  • Sheldon Cooper replaced Katie as the main antagonist on the show after she was dropped.


Katie: (sees Leonard holding a green light saber replica.) Okay, if that thing vibrates, I'm gonna need to borrow it.

Katie: Ipso facto, I drink 'til I'm flatso!


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