| Clue | Character |
| Theoretical physicist; has many idiosyncrasies | |
| Experimental physicist; very short | |
| Particle astrophysicist; can't speak in front of women | |
| Engineer; isn't a doctor; always hits on girls; allergic to peanuts | |
| Aspiring actress; waitress at Cheesecake Factory | |
| Works at university; has brief relationships with Leonard | |
| Penny's very muscular ex-boyfriend | |
| | Clue | Character |
| Penny's promiscuous friend from Nebraska | |
| Sheldon's Texan mother; very religious | |
| Dentist; went on a date with Raj | |
| Research assistant; double majored in Theater and Physics; pretended to be Sheldon's drug addict cousin, Leo | |
| 15-year-old genius; makes Sheldon jealous | |
| Sheldon's attractive twin sister | |
| Sheldon, Leonard, Raj, and Howard's boss | |
|