How do you decide the impossible? How do you distinguish shades of grey? That is the question that poses any Big Bang Theory fan who attempts to answer the question of who is the most nerdy of all of the show's main and recurring characters. The show is a triumph of geeks in the mainstream: it's not really a circus act primarily, and fans have long since committed to the characters and storylines because they're compelling, rather than just being hilariously clownish in their geekiness. But that doesn't mean the question has gone away.
Obviously there are others who don't quite qualify for the list: Captain Sweatpants is dangerously nerdy on the surface but he's basically the show's sasquatch in terms of what is actually known of him; Stephen Hawking is Stephen Hawking and Bob Newhart's Professor Proton is a nerd celebrity. But none are really in the show enough to warrant their own Nerd Factor ranking.
The same cannot be said of the main cast though: even the characters who were brought in specifically not to be nerds have - presumably by the process of osmosis - taken on nerdy characteristics and behaviours over the show's 7 years of existence. But who is the outright winner? Who is King or Queen Nerd in the Big Bang Universe? There's a good chance you already know the top spot...
10. Sheldon Cooper
Rating: 10/10
Evidence: He could well be genuinely mentally ill, but Sheldon's quirks only serve to compliment a catalogue of nerdy behaviour: he is basically an amalgamation of every nerdy stereotype and cliche that has ever been and his T-shirt collection alone is a geek treasure trove. Yes he's broken, but he's gone so far into the nerdy waters that he's genuinely an anti-hero and the show's chief selling point.