Re:Missing Option (Score 1)

I'd like to add Fistandantilus (not as powerful as Elminister or Raistlin but I like him alot), Simbul (she's a witch and chosen of Mystra more powerful than Elminster), Szass Tam (he is on the same level as Elminster) and Halaster Blackcloack (inside the undermountain he is like a god, outside he's Simbul level).
One should also not forget Vecna and Larloch.
Well IMO the most powerful in terms of power (although not very well known) is Karsus a Netheril mentalist who managed to steal Mystryl's (godess of Magic back then) mantle of divinity for a few moments.

Chris.
PS All names above are from Forgotten Realms, Dragonlance and Greyhawk