4e: The anti-minion?

Earlier today, I wrote about minions in 4e. Since then, I’ve been wondering… about the flip side of a minion. A minion is an otherwise normally powered opponent who can be taken down with a single hit.

What about an otherwise normally powered opponent who simply can’t be taken down? I’d call this a “mastermind” but that name appears to already be taken. How about antagonist?

Here’s the deal:

When an antagonist would otherwise be killed (or, perhaps, reduced to 0 hp or whatever), something intervenes and the antagonist escapes or disappears.

Would such a classification be a good addition to a game? I think it would totally depend upon play-style.