Irredeemably Evil Villains With Nothing To Sympathize With

Palpatine might have one of the highest body counts in cinema history. He is the mastermind behind the construction and deployment of the Death Star, so any loss of life caused by that behemoth (like, say, the complete annihilation of Alderaan) also lands on his head. In the prequel trilogy, it is Palpatine who corrupts Anakin Skywalker and executes order 66. He is directly responsible for eliminating one of the greatest peacekeeping forces in pop culture. 

Why does Palpatine do all this? What motivation does he possibly have to justify his actions? Well, he's just evil. He's consumed by the dark side and lusts for power and eternal life. That's it. That's the driving force behind what he does.

Pennywise is a malevolent force of ancient evil who resurfaces every couple of decades to terrorize and capture children in the town of Derby. Pennywise feeds off of the children, which gives him the energy to survive his dormant periods. This animalistic behavior is only justifiable for actual animals, but Pennywise is clearly a being of higher intelligence. Also, it's not like he just consumes humans purely for sustenance; he specifically seems to enjoy psychologically tormenting them before their demises. 

In The Lord of the Rings, great rings of power are forged and distributed to the various races as a way to rule their kingdoms. Secretly, another ring is made, a ring strong enough to control all of them. This ring is created by The Dark Lord Sauron, and he uses its power in an attempt to enslave all of Middle Earth.

Sauron was known as the "enemy of the free people" in Middle Earth. He is the embodiment of evil in The Lord of the Rings. He's more like force of nature than an antagonist since he has absolutely no qualities that a human (or elf or hobbit) could relate to. Seriously, the guy's home base was literally called "Mt. Doom." He's just pure evil with a thing for jewelry.

Freddy Krueger torments his targets by invading their dreams and making them too terrified to go to sleep.

It's not uncommon for horror films to give their villains a pitiful backstory for audiences to relate to. Well, if Wes Kraven was attempting to do that with Krueger's backstory, he failed. Krueger, while still a human, was burned alive by an angry mob. This may give reason to feel bad for him, except that he was burned alive by a mob full of parents who were angry at him for preying on their children.

While mob justice isn't normally something to support, this backstory doesn't help to get audiences on his side in any way.

Lord Voldemort sets the events of the Harry Potter series in motion with a truly unforgivable act: He tries to slay an actual baby. This is one of the first things audiences learn about him, so from that point, it's pretty hard to turn him into a redeemable character. And, to be fair, the films hardly even try. 

You may think that Voldemort's backstory in an orphanage might make him somewhat redeemable. Well, when you use your time in an orphanage to magically torment the other children, it's sort of hard to earn any sympathy. From there, Voldemort sets his sights on dominating the magical and muggle worlds, all while turning himself into an immortal dictator. So, a not-great dude through and through. 

A cartoonish film like Who Framed Roger Rabbit requires a cartoonish villain to go along with it. Judge Doom is a deranged slayer who hates his own kind. He's notorious for mercilessly erasing other toons from existence by dipping them into vats of acid, but that's not even the most twisted thing about him. In truth, he himself isn't really a human at all; he's a toon just like the ones he menaces. 

His master plan in the film involves mass-producing his acid dip and using it to wipe out Toon Town completely. Why does Judge Doom want to cause a genocide? Simply so he can invest in the off-ramp economy that the construction of a new freeway will create. Yes, you heard that correctly. Judge Doom wants to wipe out thousands so he can get moderately rich owning a few 7-Elevens.