How to Keep a Long-Running Villain Menacing, Pt. 2

Last week, I talked about how you can prevent a long-running villain from looking impotent by giving them a reason not to kill the protagonists besides being incompetent.

This week, I'll share another method that I noticed and am especially fond of: having an antagonist whose ego is so stable that it's hard to offend them, and NOTHING can humiliate them.

As with last week's method, Scorpius from Farscape and the Joker from the Batman franchise are great examples. They can be captured, tortured, incapacitated, buried, tied up, degraded, demeaned, or just about anything else you can think of... but they'll bounce right back from it, and the chances are pretty good that they were largely in control of the situation the entire time.

He lost the fight, and his prey is holding his nose within inches of a vat of acid. Guess who's in charge of this situation?

They can go from killing people and terrorizing the protagonists, to giving out hugs and filling 'bombs' with marzipan and kittens, without batting an eye or losing even a bit of their menace.

Contrast that with some of the more immature villains, who will flip out the moment somebody implies that maybe they did something nice, or if somebody defies them, or if the world gives them ANY indication that they're not completely feared and in control. They want to be scary, but to me they really just come across as being psychologically fragile, overgrown kids.

Which ones do you prefer? 

The unstable villains who lose it when their ego is threatened, or the ones who keep control of themselves and the situation, no matter what's going on?

I think it's obvious which one I like more, but I'd love to hear from you. :) Which kind do you enjoy, and why?