Honoreck was a lich who led the Grey Temple necromancers for 680 years: the longest-reigning lich since the Mage Wars. As a Thusen Draugr (A Draugr wearing Dolahan armor), he was probably the most powerful being since the Age of Mages.
For most of his death, Honoreck's influence was isolated to only a handful of Grey Temples. At the beginning of the Third Age, as more and more temples identified as 'Grey', his power spread, and by A.Y. 3272, he controlled nearly half of all Necromancy temples.
Honoreck is credited with starting the Necromanic Wars and with most of the more aweful atrocities committed within them. He promised his temples and their allies "a nation that will stand for a thousand-years", though this may be short-sighted, the Alliance having already existed over two thousand.