Zilvudar is a Drow monk of the Order of Orgolloyss. He was the Chief Monstrosity of the Order, the de facto leader. He was described as appearing as a hunched old man in a long cape, with a habit of twisting his neck in a bird-like manner. This was all a ploy, however; meant to lure both the citizenry and the enemies of the Order into believing him decrepit. He was actually taller than many Drow, standing head and shoulders above the average man, and quite physically powerful, leading many to suspect he was in fact a half-Drow, half-Human.
His methods were draconian; partially because he saw becoming the Drow's boogeyman as a duty, something that simply had to be done. The rest of it was a combination of being Enlightened and being borderline sociopathic.
Many rumors about his abilities during his rule; how he could strike stones in such a way that they crumbled into statues, how he could light and extinguish fires of any size by force of will, and most amazingly, how he could transcend time and space to exist in more than one place at once. What is confirmable about his skill is that it earned him the position of Chief Monstrosity at an extremely young age for a Monk of Orgolloyss, and his tactical strategies were what allowed the Order to so easily overwhelm the clergy of Lolth. Any that have faced him in combat are dead, and so his actual abilities remain unclear.