Professors, scientists, lab technicians and graduate students that appear in various episodes.
Analeigh Tipton as Vanessa The Mystery Date Observation a beautiful girl that was interested in physics, flags, and Klingon who answered Sheldon's dating ad.
Tom Fonss as Student The Romance Resonance who cheers Sheldon in the Caltech cafeteria.
Todd Eric Andrews as Dr. Gunderson The Workplace Proximity who was Amy's Swedish colleague that Sheldon insulted.
Ayumi Iizuka as Scientist The Workplace Proximity who was one of Amy's colleagues at Caltech.
Sophie Oda as Grace The Hofstadter Insufficiency who was a colleague on the boat during Leonard's North sea expedition.
Aaron Takahashi as Scientist The Hofstadter Insufficiency who was a colleague on the boat during Leonard's North sea expedition.
Julie Michaels as Professor The Prestidigitation Approximation
William Ngo as Chinese Grad Student The Tangerine Factor who was the Chinese graduate student confused by Sheldon's pidgin Chinese.