The user's either have magical abilities or have powers that revolve around manipulating the dead, death, the death-force and/or souls for good (i.e., resurrecting the dead), evil (in various ways) ,o r neither. They can also communicate with the deceased – either by summoning their spirit as an apparition or raising them bodily – for the purpose of divination, imparting the means to foretell future events or discover hidden knowledge.
Many practitioners find a way to cheat death one way or another, whether by becoming some form of undead creature or by bypassing their own ability to die.
Morgan le Fay (Marvel Comics) was very powerful in necromancy so much so that Doom actually traveled back in time in order to learn from her how to create an army of monsters as well as cast a spell to re-animate every person killed by the sword Excalibur by using a shard of the sword itself in an effort to create an army of the dead.
Tom (Star vs. the Forces of Evil) was able to bring long-dead martial arts expert Mackie Hand back from the dead on a whim.
Baphomet (The Wicked + The Divine) is able to summon the spirits of the dead.
Raven Hex (Tarot: Witch of the Black Rose) is a witch that follows a dark-path, and in doing so she was known for using forbidden and dark magic including necromancy to use as she sees fit.
Julius Kane (Kane Chronicles) is the permanent host of Osiris the god of underworld As the Ruler of the Land of the Dead, he has divine authority and complete control over the dead.
Walt Stone (Kane Chronicles) is the permanent host of Anubis and has displayed the ability to summon undead warriors from a crack in the ground. They can drag enemies into the Underworld. He can also summon people or spirits from graveyards, although for a short time.
Freakshow (Danny Phantom) is able to use his Crystal Ball Staff to place ghost and half-ghost under his control and make them do whatever he wants them to do.
Aside from its powerful Onmyōdō magic, Sakuyamon X (Digimon) is also said to be a skilled necromancer.
Eucliwood Hellscythe (Kore wa Zombie Desu ka?)
Keith (Fairy Tail) is revealed to be a Necromancer.
Merascylla (Nanatsu no Taizai) can raise the dead with their rage and spite powering them.
So'unga (Inuyasha) is a demon sword with tremendous necromantic powers, allowing the reanimation of hundreds of dead souls and open a massive portal to the netherworld that can absorb the entire world.
Ainz Ooal Gown (Overlord) specializes in necromancy.
Eri Nakamura (Arifureta Shokugyou de Sekaisaikyou) is a genius necromancer, who can reanimate hundreds of corpses and interface directly with the souls of the dead.
As one of the few wields of death-attribute magic, Vandalieu (The Death Mage Who Doesn't Want a Fourth Time) can take the soul of any being and use it to reanimate the dead or create Golems, Cursed Weapons or Living Armour.
Nicknamed the Boneyard Sorcerer, Johann Faust VIII (Shaman King) is a highly-skilled Shaman specializing in Necromancy, able to reanimate not only his Guardian Ghost but also control an entire army of skeletons.
The Shadow Monarch, Sung Jin-Woo (Solo Leveling) can create Shadow Soldiers and Beast from the dead to serve him.
Necronomicon Ex-Mortis (Evil Dead), the Book of the Dead.
Through a pact she made with Set, Ahmanet (Dark Universe) gained tremendous power over necromancy, able to reanimate herself as an undead, mummify people and even reanimate dead corpses that abide by her will.