Richard Feynman is something of a legend in science circles these days.  Posthumously, he became regarded as an insightful polymath, with his hands in the development of the atomic bomb (which was a real anathema to the previous generation, not so much mine and later ones) and quantum physics, along with being a musician and a student of numerous subjects.

He was also no slouch when he was alive, though far fewer people had heard of him in the broader public than reference him now.   He's so popular now they hold symposia entirely on individual lectures of his; there are more people attending lectures about his lectures today than ever attended them.    A talk from 1959 is legendary in nanotechnology.

And he was well-regarded enough during his lifetime that when the Challenger shuttle exploded in mid-air, they called him in to figure out what went wrong.

http://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers-commission...