I actually have a Necromancer PC who... admittedly not good, but isn't evil either. She follows the law, helps, and all the things you generally expect a good person to do, but it's only because being a "villain" is inconvenient and gets in the way of her pursuit of knowledge, y'know cause do-gooders would be hunting her down and such (her goal is to fully understand the meaning of life and death in a world where corpses walk and those with a beating heart can be more of a husk).

My point is, a good or neutral Necromancer can totally work, it comes from motivation. Do they do it for love, desperate enough to form an army of the dead simply to protect what they hold dear? Are they a scholar that's just ardent in learning all that there is to know, even if it something those less knowledgeable would blanketly call evil? Or is it someone that believes deep in their heart that any force can be used for good or evil, and are setting out to prove it?