You know the one I mean, typically emanates from dastardly villains gloating at thier infamous triumph. I seem to remember it had a special name all its own, something like “gloat” or “gloaming” or something like that?
Anybody know?
I don’t think you’ll find name exclusive to evil laughter but maniacal comes to mind.
Megalomanical laughter.
There’s also a variant that goes “O~HOHOHOHO~~!” 
First place I ever “heard” that laugh was in the Justice League comic books, during the period when that title was funny. It was usually Booster Gold or Blue Beetle laughing like that.
In Bollywood movies and Indian television shows, for some reason, the villanous laugh is always given an echo effect.
I’d say that gloating laughter is the most commonly used phrasing, if you are speaking of the scene where the villian has his enemy in his clutches and is watching doom overtake them.
Gloaming is a word that means sort of sunset/twilight. It’s Old English, I believe. 
It is Maniacal Laughter.
I minored in it in college. 
BWA-HA-HA-HA-HAAAAAAaaa!!
Maybe a guffaw or a chortle?
In this neck of the woods, it’s called Evil Mad Scientist Laughter[sup]TM[/sup]
Is it related to Ho-ho-ho in any way?
I mean, a guy wearing an obviously fake beard, breaking and entering into houses, and leaving so-called presents for free. There has to be a catch.
Is this laugh at all related to the Shadow’s laugh? “Who knows what evil lurks in the hear of man” and all that…
Ah, the ole BHHHH, my favorite.