The Big Bang Theory: 10 Characters You Totally Forgot Existed
9. Dimitri (The Genius Janitor)
Season 1, Episode 13: The Bat Jar Conjecture
When Caltech organises a physics quiz at their university, Leonard, Sheldon, Raj, and Howard agree to take part as a team. But when Sheldon acts like his usual controlling self, his teammates give him the boot and replace him with Leslie. Out of spite, Sheldon creates his own quiz team to defeat his friends. Just to prove he's smarter than all of them put together, his group consists of the first three people he could find, including the university's janitor, Dmitri.
But when Sheldon and his friends are unable to solve the final equation, Dimitri buzzes in and answers correctly. Even though everyone is baffled by Dimitri's answer, he points out that he was a physicist in Leningrad before moving to the United States.
The Big Bang Theory has no short supply of academic characters but Dimitri stands out since he answered a science question which stumped Sheldon - something almost no one has ever done. So, not only is he one of the smartest characters on the show, he's also among the least appreciated.