Unaired Pilot

The Unaired Pilot refers to a pilot episode which was produced to test the characters but was never aired. Only Johnny Galecki and Jim Parsons were in the cast, and the female lead, Katie, was envisioned as "a street-hardened, tough-as-nails woman with a vulnerable interior". Katie was played by actress Amanda Walsh.

They also had a female friend called Gilda (played by Iris Bahr). The show's original theme music was also different, using Thomas Dolby's hit "She Blinded Me With Science"

Plot
The episode opens with Leonard sitting in the sperm bank waiting for Sheldon to finish his deposits, which he eventually finished using a magazine of women with big butts (his fetish). At the desk, after annoyingly finishing the receptionist's crossword puzzle, they are told that they wont be paid in cash but with cheques. On there way from the sperm bank, the duo happen across a crying girl called Kate, whoes sitting on the street after a bad brake up with her boyfriend has left her homeless. Leonard invites her to the restaurant, Sheldon isn't pleased. When Sheldon can't figure out an good excuse, Leonard invites her to move into there flat.

Whilst Kate is showering a nerdy friend of Sheldon and Leonard called Gilda shows up at the flat. Gilda, who is shown to have the hots for Leonard and who fantasizing about marrying him and having kids, feels threaten by Kate's presence but relaxes after Kate says she's not interested. Kate goes out drinking and arrives back at the flat late at night, waking Leonard up by smashing a lamp. Kate starts Leonard about her life and why it sucks, using the whiteboard to explain her point. Leonard upsets her by suggesting her problems weren't caused by her mother, boy friend etc but by her making stupid decision, and she moves out. Kate comes back at the end of the episode explaining that staying there is her only rent free choice.

Changes
Whilst retaining chunks of the pilots plot, jokes, setting and characters the pilot has many difrances:
 * No Howard, Rajesh and Penny and additional characters, Kate and created.
 * Sheldon is not asexual and has a fetish for women with big butts.