I don't care how badass your characters' nicknames are, nothing can top these guys;
Napoleon, The Nightmare of Europe.
Attila, The Scourge of God.
Aurelian, The Restorer of The World.
Janos Hunyadi, The Champion of Christ.
Harald Hardrada, The Last Great Viking.
Saladin, The Defender of Faith.
Mehmud, The Conqueror.
Gustavus Adolphus, The Lion of The North.
Richard, The Lionheart.
Ivar, The Boneless.
Suleiman, The Magnificent.
This is the best in my opinion;
Otto Von Bismarck, The Iron Chancellor.