3. Leslie Winkle (Sara Gilbert)
"I'm sorry, I gotta run. If you come up with an adjective, text me" Leslie Winkle is a scientist at Cal Tech, who like Kripke is one of Sheldon's many adversaries. Unlike Kripke, Leslie Winkle strikes up a romantic relationship with both Leonard and Howard during various different points throughout the show, all the while mercilessly teasing Sheldon for being intellectually inferior to her. Leslie Winkle was a great character a strong, sarcastic, intelligent female before the likes of Amy and Bernadette were introduced properly and given the in-depth roles they have today. Sadly, Leslie stopped recurring in the series after season three when Gilbert left the show to pursue her work on her US talk show (the ingeniously named) The Talk.