The Big Bang Theory: How Many Episodes Was Sara Gilbert's Leslie In?

To say that "The Big Bang Theory" had some incredible guest stars would be a massive understatement. There are absolute jaw-droppers like Carrie Fisher and James Earl Jones; they're definitely the best cameos of Season 7. Just as exciting to see is the great Sara Gilbert as Leslie Winkle. As fans know, she and Johnny Galecki, who plays Leonard, were Darlene Connor and David Healey in "Roseanne."

Essentially the female version of Leonard, Leslie is an experimental physicist; as one would expect, she is a genius. However, unlike the awkward and nervous Leonard, Leslie is portrayed as shallow and manipulative. She has a hostile relationship with Sheldon (Jim Parsons), especially when she's able to solve one of his problems without issue. Leslie dates Leonard briefly — a fun reference to their time on "Roseanne" — and even has a casual relationship with Howard (Simon Helberg). Despite being a recurring character and being involved with two main characters, she actually only appears in 9 episodes across four seasons.

Leslie Winkle's first appearance is in the Season 1 episode, "The Fuzzy Boots Corollary," when Leonard asks her out on a date. She rejects him — though not before kissing him to see if they have chemistry — then uses him to satisfy her sexual needs. Much to Leonard's chagrin, she joins his physics bowl quiz and ends up winning the tournament for him, Howard, and Raj (Kunal Nayyar)

In Season 2, Leslie starts a relationship with Leonard. However, they don't last long because she constantly emasculates him and feels they are incompatible when he fails to back her up concerning quantum leap gravity and string theory. Leslie appears throughout the rest of the season, interacting with Penny (Kaley Cuoco) and infuriating Sheldon. Her biggest storyline is her friends-with-benefits relationship with Howard, who develops feelings for her and is crushed when she breaks it off.

Leslie appears at the end of Season 3 and doesn't return until Season 9's "The Celebration Experimentation." She arrives at Sheldon's birthday party and decides not to insult him since she's matured in the past six years. Because Sheldon is against change, she happily wishes him a "happy birthday, dumbass." Though Leslie doesn't appear in many episodes — we wish we could have seen more of her — she manages to steal every scene she's in, and it's fitting that in her final appearance, she goes out doing what she does best, messing with Sheldon.