Basic Trope: A villainous character has a code of honor in spite of his commitment to the cause of evil, and is likable as a result.
Straight: Dracūl, despite actively cultivating a villainous reputation, often refuses to commit all-out evil actions (such as killing innocent bystanders or raping women), and will explain that said actions are "unnecessary to his goal" or a "waste of resources".
Dracūl has a legitimate and reasonable disagreement with the Crystal Dragon Jesus or Powers That Be of the setting, but the god(s) he has a difference of opinion with get to decide what's right and what's wrong. An infuriated Dracūl chooses to be evil because he feels that if something that he feels would prevent needless suffering is wrong, he doesn't want to be right.
Parodied: Dracūl brags about being a genocidal galactic conqueror, and all the atrocities he's committed in that capacity... while he's climbing a tree to get a kitten out of it and giving large denomination bills/coins to all the beggars on the street.
Zig Zagged: Dracūl pretends to be noble, gets on the heroes' good side, and then betrays them. However, this turns out to shield them from a more dangerous evil. Then it turns out that the shielding was completely unintentional, and to prove it, he puts a metaphorical flag on the heroes, calling that greater evil right to them. However, this is, in and of itself, a Batman Gambit: just as he expected, the greater evil interprets that flag as a trap, and avoids the heroes because of it.