In the series River knows. In real life, if it even exists only Stephen Moffet knows. It is like a state secret. If you know before it is ready to come out, they'll probably kill you. So, you know, basically no one knows. The Time Lords did know his name, but no one other than River.
posted over a year ago
Though the Doctor is the only one that is still alive as we see her younger self and her ghost as she dies in the Library saving the Doctor
Except for River no one except the Doctor knows, the world will supposingly end if the Doctor's name is spoken out loud. The only known name he has is a nickname and a false name, the nickname is Theta Sigma, Thete for short, he was called that at the Academy on Gallifrey. Then there's John Smith, the name he uses when he has to have an actual identity, because the Doctor isn't a suitable name. The Doctor is his chosen name though and he's almost completely rejected his real name.
