Gilda was the scientist colleague’s name in The Big Bang Theory’s original unaired pilot.
Gilda was played by Iris Bahr and was presented as a colleague and friend of Leonard and Sheldon. Unlike Katie, the woman they meet in the apartment, Gilda belonged to their scientific and academic world. Her interest in Leonard also created a romantic tension that helped shape the unaired pilot’s very different storyline.
Gilda disappeared when the pilot was substantially rewritten. The revised version introduced Penny, played by Kaley Cuoco, and expanded the central ensemble with Howard and Raj. Gilda was not simply renamed Leslie: Leslie Winkle was a separate physicist character who appeared later in the broadcast series and was played by Sara Gilbert.
The unaired pilot is often discussed because its characters and tone differ sharply from the long-running sitcom. It used Katie and Gilda instead of the familiar Penny-centered setup, and it portrayed Sheldon very differently from the character audiences came to know. Gilda therefore belongs to the show’s early development history rather than its regular televised continuity.