Baron Vladimir Harkonnen (Dune series)
You can’t get more evil and disgusting than Vladimir_Harkonnen: a face covered in blistering diseases, killing his servants for pleasure, ruling with terror, appointing his family members positions of power, is a long list.
Emperor Palpatine (Star Wars series)
This guy doesn’t need an introduction. Emperor Palpatine started his political carrer as Senator from Naboo and then manipulated his way up to become Supreme Chancellor of the Galactic Republic first, and then Emperor of the Galactic Empire.
Big Brother (1984)
Big Brother is the leader of the totalitarian state in Oceania. Despite the comforting name, Big Brother’s ruling oppressive and despotic.
Ming the Merciless (Flash Gordon)
Ming ruled a whole planet, Mongo and was the villain of Flash Gordon serials. To be honest, Flash did land in Mongo uninvited and unannounced (in the original comic strips), so what’s a guy with a name like the Merciless gotta do but retaliate?
President Snow (The Hunger Games series)
North America has become a dictatorship and President Snow is its ruthless leader.
Dr. Doom (The Fantastic Four)
Doctor Victor Von Doom rules the country of Latveria with an iron fist. As it is the case in most megalomaniac dictatorships, the populace is poor and fully dependant on their tyrant.