If it's crap ... We'll tell you
I not sure if this has been done, but here it is regardless.
I think that more often than not a villain expressing themselves in song is the single greatest moment in most movies, whether their Disney or Non-Disney. They are either hilariously self-unaware, campy, or downright fucking creepy, and it's a nice breakaway from the mostly boring protagonist.
So let's try to gather them all in one place.
My personal favorite:
Anything Tim Curry has done
Anything besides that thing he did for Beauty and The Beast: The Enchanted Christmas. I call it a thing cause I doubt to this day that it was an actual song meant to entertain people.
I've been looking out for this one. I remember seeing it as a kid and being kind of freaked out by it, especially when he locks himself into that red thing and does the evil laugh. Thank you.