Karen: The idea of a scientist-hero probably took root in the 1950s, after the development of the atom bomb and during the Space Race. Plenty of sci fi films of the 50s and 60s depicted these noble men of science -War of the Worlds, Earth vs. The Flying Saucers, This Island Earth, just to name a few. Marvel and DC both picked up on this concept. Reed Richards is the direct descendant of these films, using his considerable scientific know-how to explore and change the universe around him.
But there are many others who fit into this category. All men (and unfortunately, only men) of vast intelligence, whose brains are just as potent as any super-power. At Marvel, besides Richards, there's also Tony Stark, Bruce Banner, Hank Pym, and on the dark side, Dr. Doom. The Black Panther is also a genius, and lately the Beast has been accorded the honor of being called one of the smartest people on the planet.
At DC, there seem to be fewer characters in this mold, but there are some that sort of fit. You'd have to say that Batman qualifies as brilliant. And what of Lex Luthor?
So of all these brainy guys (and all the others I've left out), who is the brainiest? If you want to break it down by company, be my guest. And let's just talk about human beings -no aliens or conceptual beings please! And why haven't any female characters joined their ranks?