(IN NO PARTICULAR ORDER)
1) Jhin (League of Legends) He may be a minor villain in the story, but he's one of the most disturbing villains I've seen. He kills people and makes it "art". He also happens to be my main. He's fun to play.
2) Ganondorf (TLOZ Series) He's Ganon. King of Evil. And a demon pig. Enough said.
3) Makuta Teridax (G1) He enslaved the entire Matoran universe. He betrayed his brothers/sisters. He was just overall a bad guy.
4) Dr. Eggman/Robotnik (Sonic Games) P̶I̶N̶G̶A̶S̶ OOOOOH My childhood is here. I loved the Sonic games when I was younger (I only played Modern Sonic until recently) and this guy. Was the most ridiculous villain ever. He was consistently funny, while not being afraid to have dark plans sometimes. cough cough Sonic Colors cough cough
5) Dr. Robotnik (Archie Comics/SATAM) Okay, I don't know if this is cheating, since this is Eggman in the Archie Comics (RIP) and SATAM. But holy cow this guy was threatening. Seriously, just listen to his theme or watch this clip. It's intimidating.
6) Bowser (Mario Bros.) Needs no introduction. He's evil turtle who wants a princess. Sometimes he makes galaxies.
7) King Dedede (Kirby) I LOVE THIS GUY Now I love the Kirby series to death, but this is the best character from it. This guy is barely even a villain, there's a few games where you can PLAY as this guy. He's still evil sometimes. Plus he's my main in Smash Bros. He's fun.
8) Umarak (G2) He's spooky shadow man. He has a nice voice. He is also spooky monster man. Spooky.
9) Kaos (Skylanders) Suprisingly, I don't hate this series! But I do hate this guy. He's annoying, pretty much has the same plan every game with some minor tweaks. The only exceptions being Superchargers and Trap Team, as in Superchargers he isn't even the final boss, and Trap Team he's the SUPRISE final boss! Well, at least he's OP when you can play as him.
10) Zant (TLOZ: TP) This guy is a calm, collective villain. NOPE HE'S A PSYCHO KING GUY