Count Dreskar was a wealthy slave trader, and associate of Al Misurata. He resided near Piran, Slovenia.
Dreskar is never actually portrayed, only referenced in terms of complete mystery. In literary terms, he is what's called an "unseen character". His main aide was Ferenc Kuvan.
Dreskar is integral to Voyage of Slaves in that Misurata attempted to sell the Travelling Rizzoli Troupe, as well as Ned and Ben to him.