Well, to the average layman, I agree, Joker is most well known. However, that goes for alot of Bats villains. Penguin, Mr. Freeze, Riddler and Two-face are all very well known. Moreso then Catwoman? Joker, for sure. I don't know about any of the others.
But, right now, Magneto is very iconic as well. He might be seen as an anti-hero to those whom take a closer examination, but again, to the average passerby, he's the X-Man villain from the movies.
I'd have to say Joker is the most "iconic", as far as being the most recognized supervillain across both generational and pop cultural lines. Members of Batman's rogues gallery (Penguin, Riddler, Joker, Catwoman) were household names since back in the 60s with that campy Batman series starring Adam West. Another big time comic book villain is Bluto from the Popeye comics. He's "Iconic", if not "archtypical". I'd say it goes:
1a-1d) Batman's Rogue's Gallery (Joker being best known, followed by Catwoman, Penguin, and Riddler).
2) Lex Luthor (You don't go up against the best known superhero for nearly a century without becoming a household name).
3) Megatron (Transformers are very, very, very big worldwide. Everyone knows who Megatron is [and everyone also knows the sound that Transformers make when they transform]).
4) Dr. Doom (Doom is the archtypical super genius villain, and appeared in just about every Marvel Hero's rogue's gallery at one point or another just to lend the hero credibility).
5) Shredder (Teenage Mutant Ninja Turtles main villain. Highly recognizable and widely known).
6) Cobra Commander (Among people age 24-50+, he's extremely recognizable. To the younger generation, not so much).
7) Bluto (Everyone knows Popeye, and everyone knows the guy that he used to punch around 24/7).
8) Magneto (Outside of Xmen fans and people that have seen the films/cartoons, he's not as big or easily recognized as the people above. When you say "Megatron" or " Cobra Commander" to someone they immediately know who your speaking of. Magneto also, but not to as great of a degree. My Mom knows who Megatron and Cobra Commander are based on name dropping alone.).
Will think of more. I didn't include Doomsday or Bane because they aren't so much "iconic" as much as they are the villains created for very high profile comic book events and therefore are well known. Doomsday only known for "killing" Superman and Bane is only known for breaking Batman's back. Other than that they aren't known widely for anything more to your common observer.
Who the f**k is "Cobra Commander"?
Anyway, there really is only one villain that fits the profile of "Pure Evil" .... think about it, whose very existence says "I'm a villain" more than........
whistling
betcha can't guess what's coming
😈
SWARM!!!
I mean COME ON!!!!...he's a freakin' Super-Nazi ........... made out of bees!!!!
Betcha thought I was going somewhere else with that!
😛