@Kaarme
True most necromancers are evil, (witch i'm pretty miffed about because you don't have to be inherently evil to use undead/soul/life manipulation magic.... )
As for the corruption it's usually in the form of making them more cold and soulless like in Overlord or if a few cases makeing them obsessed with things they care about.
Both pretty common big bad evil guy traits.
Usually necromancy is frowned upon at best and taboo at worst in most fiction, Witch is the reason only the evil and selfish tend to use it for the most part.
Haven't stopped me from being a goody two shoes necromancer who goes around asking the dead if they are ok with me useing his or her body for the greater good.
But i digress.
There are a few exceptions, like the necromancers from the diablo universe but most necromancers in pop culture are evil.
Wiz from konosuba is also supposedly a good lich if i dont remember wrong, but its the only one i can remember of the top of my head.
I say supposedly becouse she dont really look undead at all, but they call her a lich and she do have the magic for it so.....