The only games I've been able to play on my computer recently have been Diablo 3 and Guild Wars 2. In both of these games, there is a class that specializes in necromancy. In Diablo 3, they are called witch doctors, and in Guild Wars 2, they are simply called necromancers. These professions possess skills which allow them to summon undead creatures to fight for them.
The witch doctors in Diablo 3 seem to have been directly inspired by Haitian vodou.
The major skills witch doctors have are to summon zombie people and dogs to fight on their behalf. This invokes the idea of master and forever-slaves in vodou. The zombie dogs follow the player around and be sacrificed to do burst damage, while the zombie people are summoned momentarily to do burst damage or to impede mobs, disappearing back into the ground afterwards. Additionally, many of the witch doctor's other skills deal poison damage, which perhaps is a reference to the idea in vodou where poisons were used by bokors (vodou sorcerers/priests/priestesses) to create zombies.
The necromancers in Guild Wars 2 possess similar skills to witch doctors. One build for necros in this game is to focus on being a minion master. Minion master necros summon undead minions to fight alongside the player. These minions can also be sacrificed. For example, one necro healing skill is to summon a creature that heals the player in ticks while the player attacks, but the creature can also be sacrificed to give a burst of heal. There is also a condition damage build for necros, which allows players to deal damage in the form of bleeds, poisons, etc. They seem to be less obviously inspired by vodou though.
(I still made the connection and named my necro Bare on Saturdays, complete with a top hat).
What perplexes me about necromancer professions in video games is this: why aren't the necromancers able to manipulate the zombie mobs? In Guild Wars 2, there are entire zones where the only mobs players will run in to are zombies, yet necros are not able to seize them. In Diablo 3, I believe there are only zombies in the first act of the story, but witch doctors are not able to take control of them either. Perhaps it has to do with who summoned the zombies. In Guild Wars 2, they are under the influence of a dragon named Zhaitan. In Diablo 3, however, I don't think we were ever provided with a back story, so they might have been masterless zombies, so... can I has?
Your post made me think of a story I read awhile back about magic/poison/plagues in video gaming. It was about something that happened in World of Warcraft:
http://en.wikipedia.org/wiki/Corrupted_Blood_incident
A high level plague-effect escaped its dungeon through a glitch, and ended up spreading across the continent, decimating the population of lower-level players. It was realistic enough that epidemiologists researched the event. Maybe part of the reason that mobs aren't generally take-over-able is the repercussions for the wider virtual world(Idk if guild wars is multiplayer or what). In the wow plague, some players deliberately infected themselves to spread it. If you give gamers an inch, they will find an exploit for it, multiply its power, and destroy your game with the weight of 10million yardsticks.