Lullabee
Celes__Chere
Doesn't he run into someone who calls him by his real name as the fourth doctor? Began with a t I believe... I'd have to rewatch it to be sure though.
Theta Sigma (ΘΣ, if that shows up), but it's doubtful that's his real actual name. Just another nickname or something of the sort. It's two Greek letters, so perhaps a fraternity name? xd Which tends to make me think of a much younger version of the First Doctor passed out on a threadbare sofa wearing a toga. Or going on road trips. Living on ramen and beer. Running across the quad naked. Maliciously forgetting pledges' names...
And, why, of course Time Lords use Earth's Greek alphabet!...The First Doctor passed out on the sofa, wearing a toga.
whee I like to think that the Time Lords picked the bits they liked out of other cultures, and they created their own sort of fraternity system.