I need a name....

Thanatos (Θάνατος spelled in greek) means actually death..
Ares (Άρης spelled in greek) is the god of war in the ancient greek mythology
I don't know if you like them for your character..but I would personally use one of those for a character like the one you described :)
Hope I helped :)

Adrian     dark one
Blade     knife
Braeden     from the dark valley
Bran     raven
Brend     little raven
Brendan     (little) raven
Brone     sorrow
Condon     dark-haired wise man
Corbett     raven
Corbin     raven
Corey     raven
Crevan     fox
Daray     dark
Darcy     dark
Daren     born at night
Delano     of the night
Donovan     dark warrior
Douglas     from the dark water
Doyle     dark stranger
marreco, drake     dragon
Duglas     dark stranger
Duncan     dark-skinned warrior
Gregory     vigilante
Hadrian     dark one
Karan     tyrant
Keegan     little fiery one
Keir     black
Keiran     little & black
Kiernan     dark-skinned
Kern     dark
Kerr     marshland
Kione     someone who comes from nowhere
Maurice     moor
Nigel     dark
Remington     from the raven estate
Raven     like the raven
Ryu      void, dragon
Than     death

Or try thinkbabynames.com
you can procurar names por meaning like "dark," "mysterious," etc.

Any name can will do really
How about Steven Demitri
Thomas Bedwin
Maximillian Field
there is a website where you can find the meanings of names
its called www.thinkbabynames.com

Derek Myrick
Vincent Muller
Seth Matthews
Shane Oakley
Leroy Pruitt
Zander Knigston