It's easy to throw monsters and Big Bads at your player's characters, adversaries who will simply do anything they can to kill them as quickly as possible. They'll use any dirty trick they can, any sneaky means at their disposal, any evil trap for the unwary PCs. They'll outgun them, hit them with their full strength, spare no expense, and hold nothing back. They'll kick the PCs when they're down. They'll be evil, nasty, rotten, wretched, and downright mean. They'll make false promises, break their word, engage in extortion, blackmail, torture, and slander. You won't be able to trust them as far as you could spit them.
Which is all well and good as far as it goes.
But if you want to make a villain, give them a sense of honour.
If you make your villains honourable in some small way, there will - inevitably - come a time when they can rub the heroes' faces in the fact that they have behaved in a way which is better than the PCs.
If your players care about their characters to any extent more than a hack-and-slasher, this is pure gold.
GM: You hear them talking over your listening device.
Boba Fett: Aren't we going to destroy his ship?
Jango Fett: No, I gave him 10 minutes. There's still 30 seconds left.
Jango Fett: I won't stoop to his level and blow something up before he's ready.
Boba Fett: So we wait, and then blow it up?
Jango Fett: Nah, one of us is still honourable. In fact, let's make it interesting.
Jango Fett: Hey Kenobi, we're going to Geonosis. Hear that? Catch us if you can.
Obi-Wan: Look, that's totally unfair!
Obi-Wan: Firstly, we never knew you were on the HQ ship.
Obi-Wan: Secondly, you'd have done the same in our position.
Obi-Wan: Thirdly, I was not in charge.
Obi-Wan: Fourthly, the fighters were sent to assassinate the leaders, not blow up the ship.
Obi-Wan: And fifthly—
GM: You do realise he can't hear you?