Does anyone recognize his voice, or do we already know who voiced him?
Is this particular voice actor already featured in the game - I'm rather certain that I've heard his
voice before.

Whoever it is, he is a great choice of voice actor for the role of Harkon. Bloody briliant to be frank!

The english voice is very good indeed but the german one,not so much(german here)

Ive read in this same forums that this voice is the Molag Bal's voice, but I disagree, also I don't believe the voice actor is already in game, in anyway it sounds very dark and totally fits the role. Now just waiting to hear more lines so we can have a better idea of who is voice acting for him.

The voice is good though not Simon Templeman good but still a good voice for a vampire lord.