Ming the Merciless.
As a child I recall my dad telling me of the ultimate baddy from his fave serial of all time, the original Flash Gordon from 1936, starring Olympic swimming hero Buster Crabbe.
See a clip:
These serials- Flash Gordon, Buck Rodgers (also with Crabbe), The Phantom Menace, and many more) were not only staples of movie theaters in the 1930s and 1940s, but of early morning public television on weekends in 1960s and 1970s New York City. Watch any one of them, and they are so much more inventive and operatic than the lame shit that was Star Wars. Toss in the Yellow Peril meme, and fun galore. And, interestingly, George Lucas touted his crap (a blatant ripoff of Isaac Asimov's Foundation books) as being more realistic than these serials because of the then state of the art special effects. Yet, if one looks at the original 1970s effects, they are as badly dated as these are, but they don't have the fun stories and 15 minute episode structure to fall back on.
This was essential storytelling, something modern cinema lacks. Is it any wonder that Lucas keeps revising his older films, mostly with updated special effects? Why? Because the actual story sucks ass! Charles Middleton, however, as Ming, kicked ass!