I'm playing my first 'evil' character.

I'm picturing him as like an 'Anti- Dr. Who' who WANTS to use violence to alter the world.

Who shouldn't I kill? I mean, is there any quest giver that I should WAIT to kill, or never kill?

Thanks.

It might be easier to approach by doing the questlines you have in mind before you take out random NPCs. There are just too many quest related NPCs to reasonably compile a do-not-kill list.

Even when playing evil you don't have to kill anyone unless they attack you first or you are told to kill them via a quest (join the DB for this option).

It sounds like you just want to play a psychotic killer, killing for no apparent reason at all. Granted that is evil, but not everyone who's evil is a psychotic killer.

If you just kill random people you will soon find that there are many people in Skyrim that you just can't kill, the Essentials. The essential status prevents you from killing 'important' NPC's. But again, why just kill random people?

It's your game, if you want to commit mass murder and wipe out 90% of the population of Skyrim, go ahead.

My evil characters often have a reason for their actions, and they kill only when necessary. Even the Master from 'Doctor Who' (who is basically the anti-Doctor) doesn't randomly kill people. He'll find ways to gain control and rule over people, he prefers it that way.