Hesperdan

Hesperdan was an archmage in the Zhentarim. He was considered by some to be perhaps the greatest tyrant mage in all of Faerûn. He also went by the alias Gelvar Thordrunn, a dealer of magical curios and esoterica in Ordulin, Sembia.

History
Hesperdan, in the guise of Gelvar Thordrunn, took on Malathar Wingstarl (later known as Sememmon) as an apprentice, teaching him wizardry. Gelvar disappeared, believed lost at sea, two years after taking on Malathar, some time between 1234 DR and 1258 DR.

Hesperdan schemed to bring Fzoul Chembryl to power in the Black Network, thus allowing him to use Manshoon for his own purposes. He did much behind the scenes to foster Semmemmon's rise in the Zhentarim ranks and indirectly sought to mould him to be a foil for Manshoon.

Once, speaking to himself, Hesperdan implied that he might not be considered a "man" after all. Indeed, in 1479, he revealed that he was also the black dragon called Alorglauvenemaus, having mastered the ancient elven magic of weredragoning. His main concern was the plots of Vangerdahast of Cormyr, whom he considered more dangerous than the Zhentarim. He died that year fighting with Elminster and some War Wizards of Cormyr.