I have decided to try and defeat all the human and undead bosses in the game (I don't care for the creature ones). I must be nuts...
Well I have defeated these wons so far:
Ian Ramjaw
Gideon Grog (invasion)
Francis Faust (invasion)
Edward Lohand
Neban the Silent
Remington the Vicious
Samual (who hasn't?)
Claude D'Arcis (again, who hasn't?)
El Patron (and not on my first try :)
General Hex
General Darkhart (who hasn't, again and again and again)
Undead Timothy Dartan
Krudel (he is listed as a boss but i dont think he was)
Stench (near Darkhart is where i saw him)