Joyce Kim

Joyce Kim (Ally Maki) was one of Leonard's former girlfriends and a North Korean spy. The two dated for 27 days, after which Joyce defected back to North Korea, as Howard and Raj recalled in "The White Asparagus Triangulation" (S2E09).

Overview
Joyce Kim was mentioned in the pilot (S1E01), "The Codpiece Topology" (S2E02) and "The White Asparagus Triangulation" (S2E09). She appears in flashbacks shown during "The Staircase Implementation" (S3E22). In 2003, Leonard was working on rocket fuel at the time under a DARPA contract and Joyce Kim was a spy attempting to obtain information on his work by seducing him and report it back to her government. Luckily, Sheldon unknowingly stopped her, after he intruded on their fun, claiming Leonard had violated the roommate agreement. Leonard agreed to give Sheldon a 12 hour notice before having guests over, but he hadn't known Joyce Kim for 12 hours before he had her over. It is unknown when she will appear again, if ever.

She is alsomentioned by Sheldon during Howards Job interview