Since, I've already posted about my favorite villians, I'll give you a general idea of the sort of villian I like to create and /or read. He or she must have these essential parts to catch my attention, regardless of genre or novel length.
History- What made them the person they are? In tiny bits of information if you please.
Depth - Bad guy or not they still need to breathe.
General nastiness with purpose ie. Make the hero work for it, nobody wants a spineless villian.
I've seen good ones, bad ones and those that be "Geez put it back on the shelf." Make them strong, nasty and terrying and I'll be entertained. Have a great week y'all.