Actually not true, Clark Kent/Superman is really the smartest. Ever see Superman 4? Christopher Reeve battles Nuclear Man? He knew exactly how to destory Nuclear Man.
Lex Luthor (Gene Hackman): "Wait, how did you beat him?"
Superman (Christopher Reeve): "High School Physics Luthor, well you figure if your a creature born from the sun then its obvious that sun is the source of your power."
Superman: "See you in 20."
Smartest in regards to book smarts? Reed Richards
Smartest overall, including psychology and street smarts? Batman is leagues above everyone else.
Reed would be able to out-build Batman in crazy technology, but Batman would be able to convince Reed to build one for him in the process without knowing it lol. Its that kind of thing where Bruce is an incredibly intelligent guy, but Reed comes up with extradimensional shit and this wacky cosmic stuff which has to be more complicated.
Villain-wise? Dr. Doom and Lex Luthor, most likely. There's a reason why Doom is Reed's archenemy and why Luthor is such a threat without having any powers.
People like Parker, Pym, and Banner, have shown that they're really smart, but in particular fields and not well-roundedness. People like Pym and Palmer are obviously smart because of how they've created/manipulated their source of power, Banner's great for his field, and Parker's a gifted mind, but if you need someone to build you a plot device, you ask Reed or Bruce lol.
Um....are you guys retarded??? Superman's brain processes information a LOT faster than any human and he also has super intelligence in his "power list". This make Superman the smartest hero/villian ever. The second would be Reed Richards, then Batman, and then Tony Stark. There are so many genius heroes and villians that I shouldn't even go into it any farther.
If we don't count cosmics:
Superheroes:
- Reed Richards tops them all.
- I'll say that Bruce Banner comes second, with his recent feat, which are completly over-the-top.
- In the third place, I'll say it's a tie between Iron Man, Batman, Hank Pym
Villains:
- Dooms tops them all.
- I'll say that Lex Luthor comes second.
- Tie between the Leader, Osborn, Joker