Oh this will be a tough one...
10) General Grievous (Star Wars)
Cool-as-heck design, curb-stomped like a boss in the 2005(?) Animated Series, but severely limited in the films and CGI series. Neat backstory as well.
9) Davy Jones (Pirates of the Caribbean)
Awesome design, and was an interesting villain. Wish he had more screen time. (though if the ending of 5 is anything to go by...) Bonus points for playing his own theme on organ.
8) Ragyo Kiryuin (Kill la Kill)
Just for the fact that every time she was on screen I prayed for her to get brutally massacred. Stupid rainbow-haired genocidal maniac. And also abusive mother. Hate you so much Ragyo....
7) Sauron (Lord of the Rings)
Just good ol' fashioned dark evil force. Bonus points for literally just being a huge tower with a flaming eye on it.
6) Tricky the Clown (Madness Combat)
Oh my god this clown. Psychopathic mayhem machine with the ability to bend the laws of reality at his whim. Also a zombie. Who also becomes a giant flaming demon. He also was a DJ at some point. Man this series was weird.
5) Aku (Samurai Jack)
One of the best Cartoon Network villains ever made. Both comedic and terrifying, his presence was just as important as Jack's. With Mako Iwamatsu's phenomenal voice-acting, Aku really cemented himself as one the top cartoon villains. Bonus points for meme material.
4) GLaDOS (Portal 1+2)
Corrupted supercomputer with an itch to run tests and a sarcasm level of over 9000. Made almost all the memorable moments in this franchise's history. For science... you monster.
3) Ramsay Bolton (Game of Thrones)
...You know why he's here.
2) Griffith (Berserk)
Charming leader of the Band of the Hawk. Betrays all of his fellow friends and soldiers to a horrible massacre as he ascends to become one of the demonic God Hand. Does really... really... bad stuff. Yet, he saves the kingdom of Midland from invasion by an even worse scumbag, unites humans with Apostles, and creates an overall peaceful society...
So is he really a bad guy in the bigger picture?
Yes he still did horrible stuff so I wait anxiously for Guts to take revenge.
1) Yoshikage Kira (Jojo's Bizarre Adventure; Diamond is Unbreakable)
Ohhhh he's such a good villain. No ambitions, no schemes or hunger for power. He just wants to live a quiet life. And also kill women, steal their hands and... yeah.
Why he's number one for me is that I was actually able to connect to his character. (Minus the murdering and the hand obsession)
The idea of just wanting to be left alone by society, to live a stress-free life and be able to do whatever you wanted at your leisure; it's not too far-fetched for most people to want that. So while he's a terrible human being and deserves his fate in the end, part of me got really invested in him as he attempted to maintain his tranquil routine, or tried to replace Kosaku later on (and maybe even begin to feel things for Shinobu? OOOOOOH).
Bonus points for looking like David Bowie, having a cat-man ghost named after Queen songs blow stuff up, and having an awesome fashion sense. Seriously, I have no regrets buying the Killer Queen ties.
Honorable mention goes to Dio Brando/DIO/Diego Brando/Heaven Ascension DIO.
Because it's Dio.