I'm wondering whether there is some convention for using sort tags where the names don't really have a first name, but rather use an adjective, or a title, etc...
* Lady Gaga
* Weird Al Yankovic
* The Notorious B.I.G.
* Sleepy Brown

I always only used the last name, when it was clear that it was a First Name / Last Name thing. However, sometimes it's not clear at all whether something is a first name or just an adjective / calling name. I had occasions before (though cannot remember the exact cases now) where for long I thought someone's name was an artist name with some adjective, when it turned it out it was their real first name.

At the moment, I'm more inclined to sort the above names based on the last name (or at least main part of the name) rather than as-is. When you look at Wikipedia, you see in the articles these persons also referred to as 'Gaga', 'Yankovic', 'Brown', etc.. which would warrant sorting them there.