Tough to narrow it down! Let me answer without my engineering hat on!
Joss Whedon is a definite hero of mine – Buffy the Vampire Slayer, Firefly, Dr. Horrible’s Sing-Along-Blog – all works of greatness.
Can I put the Mythbusters as one hero? I think they do amazing work bringing engineering and science to the world in a way that is always fun, exciting and engaging. Plus they blow a lot of things up with explosives – that’s always a good thing.
Lastly it would have to be Stephen Fry. What a guy.