The ends justify the means is a common phrase, and your Villains could transcend the role of just “Bad Guy” to be truly fleshed out people. Someone trying to accomplish good but willing to use evil is a conundrum.

If an NPC is trying to do something good, like stopping rampaging wizards who are trying to lay waste to an entity city, that’s okay.

But if that person is willing to do evil to accomplish this goal, like sacrificing people, stealing, using evil magic or magic items, etc, then that’s bad.

Perhaps your “Villain” isn’t Evil at all?

Instead of using a Lawful Evil, Neutral Evil or Chaotic Evil alignment what if they were Chaotic Good and simply used evil means to justify the good end they were aiming for?

Here are some great traits some “Good” Villains might have that makes them Bad:

1. Rich and greedy and spends money to hurt others
2. Bullies others
3. Gets undeserved rewards
4. Responds badly to being questioned
5. Disregards or punishes those who disagree
6. Oppressive and controlling
7. Says one thing and does the opposite
8. Frivolously changes mind
9. Eats, spends, consumes when others are hungry, poor, without
10. Punishes innocents
11. Supports inequality
12. Rewards unfairly
13. Cares not the effects their words and actions have on others
14. Makes unfair rules and laws
15. Doesn’t follow their own rules
16. Lies for self-benefit and believes their lies after awhile
17. Is above the law and cannot be punished
18. Switches sides – traitorous
19. Lazy and makes others do all the work
20. Chooses sides for bad reasons
21. Distrusts everyone and constantly tests for loyalty and obedience
22. Has others fight their battles
23. Uses blackmail and extortion to get their way
24. Rejects and abuses the rights of others
25. Doesn’t take responsibility for their decisions or actions
26. Suppresses freedoms
27. Makes offensive jokes
28. Plays favourites to evil or incompetent minions
29. Enforces their twisted version of normal
30. Endangers others frivolously
31. Indifferent to the struggle they cause others
32. Does not listen to reason and makes bad decisions endangering others
33. Sacrifices others for their own ego or vanity
34. Physically, emotionally abusive
35. Spoiled and pampered and lashes out when demands not met
36. Keeps others as toys or decoration
37. Values appearances over character
38. Must kill to feel good about themselves
39. Starts or supports war
40. Responds well to gifts and flattery
41. Expects adoration and punishes when not given
42. Has short fuse, temperamental
43. Flirts or seduces to get their way
44. Stays unpredictable to keep others off-balance
45. Hurts other purposefully
46. Supports anarchy and destruction
47. Destroys property punitively
48. Bribes others to do their bidding
49. Endangers others capriciously
50. Gossips and ruins reputations

Credit to Johnn Four from Roleplaying Tips and creator of Campaign Logger for these 50 traits.