Joyce Kim 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." She has been mentioned several times and seen once.
Joyce Kim was mentioned in the pilot, "The Codpiece Topology," and "The White Asparagus Triangulation." She appears in flashbacks shown during "The Staircase Implementation." She was portrayed by Ally Maki.
In 2003, Leonard was working on rocket fuel at the time under a DARPA contract and Joyce Kim was a North Korean spy attempting to obtain information on his work by seducing him and report it back to the North Korean regime. Luckily, Sheldon unknowingly stopped her, after he intruded on their sexual Intercourse, 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. She did not appear on the show again after this.
Later in "The Apology Insufficiency," she is mentioned by Sheldon during a meeting with the FBI.
- In the flashback episode "The Staircase Implementation", Leonard says that he had known Joyce Kim for only 12 hours, though previously it was stated that they were together for 27 days in "The White Asparagus Triangulation."
- In "The Staircase Implementation," Leonard says Joyce Kim was a North Korean spy, though in "The White Asparagus Triangulation," it was stated that she defected to North Korea while dating Leonard. The word defect implies a change of (military) allegiance, whereas a spy's allegiance never changes, only is kept secret while on a mission. This may be an inappropriate use of the term defect, as Joyce is otherwise always spoken of as if she were a spy.
- It is likely that Joyce Kim was executed upon returning to North Korea due to the NK regime having an infamous and extremely-low tolerance for failure and would highly likely find being unable to tolerate a pesky roommate an unacceptable reason for failing to obtain US Government secrets from a scientist involved in a government project. Even if she was directly related to Kim Jong-il (since Kim is actually the family's surname), nepotism has not prevented members of the Kim family from being targeted for assassination, as evidenced by the 2017 assassination of Kim Jong-nam.
|The Big Bang Theory Episodes|
|Young Sheldon Episodes|
|Appeared||M = Mentioned||Did not appear||Not aired/Not available|
|V = Voiced||C = Cameo||F = Flashback||I = Indirectly mentioned||P = Pictured|