No contest. Its Darth Vader. Especially with the end of Rogue One showing him in true badassery.
But really that music, the breathing, the voice, the cold mechanical presence coupled with religious zealotry, the sheer power, and callous disregard for life.
Think back to when you first saw him. He is the reason the Star Wars universe was truly successful.
Honorable mentions:
Blofeld and Goldfinger from the Bond films
Michael Myers(really set off the Slasher genre), Bates as the OG.
Thanos
Dracula in various eras( Chistopher Lee for me)