Quotes: Only Known by Their Nickname

Karrde: We haven't yet been able to decipher the message, but it definitely contained Thrawn's name. His full name, not just the core name 'Thrawn.'
Han Solo: I didn't even know he had more name.
Karrde: Most people don't.

We're the thin/fat gay married Anglican Marines. Why would we need names as well?

"My nickname's Boss! Even the author doesn't know my real name!"
Boss, Shin Mazinger

Spiros: He knows my name. But my name is not my name. And you? To them, you are only "The Greek."
The Greek: And, of course...I'm not even Greek.

"He asked me to stop calling myself Blackfish. Said it was an old joke, and never funny to begin with. I told him people have been calling me Blackfish for so long, they don't remember my real name."
Brynden Tully, Game of Thrones