Dennis Kim

Dennis Kim (played by Austin Lee) is a 15 year old genius from North Korea whom Dr. Eric Gablehauser hopes to recruit into their Ph.D. program. (The Jerusalem Duality) Dennis and Sheldon have an antagonistic relationship when the former excels Sheldon in every way. Losing faith in his own research, he annoys his circle of friends and colleagues by visiting them and criticizing their work (prompting them to say "Go away!" whenever he's around). Deciding his work in physics is useless, he decides to aim for the Nobel Peace Prize by creating a 'Nuevo Jerusalem' for the Jewish people in the Mexican desert (thus creating peace in the Middle East).The guys make arrangements so Dennis can meet girls of his age and get distracted of his own research so that the old Sheldon would return. The plan succeeds and Dennis is seen kissing with a girl, no longer an intellectual threat to Sheldon.

It is very possible that he is a North Korean spy like Leonard's former girlfriend Joyce Kim but their is no evidence to support that he is a spy.