A Necromancer is the most feared type of Free Magic sorcerer, and the enemy of the Abhorsen. They use the bells like an Abhorsen, but use Free Magic unrestrained by Charter magic. Necromancers specialise in raising the Dead and Free Magic elementals to serve them, from Dead Hands and Shadow Hands, to Hish and Stilken. Necromancers fear Death and do anything to survive longer. For example, Hedge was over 100 when he died.
These are all the necromancers who have been metioned.