As he has just died yesterday, I'd like to add Patrick Moore to the list of scientific heroes. Maybe not famous outside the uk, he was the face of astronomy for many, many generations of us budding "astronauts and astronomers" (heck, scientists as a whole I would imagine!). Every person who studied science at university knew about him. He was a legend. And a great eccentric, backed by a steely determination that science would get us there in the end.
It's really sad, but the night before he died I was taking star pictures with my new camera. the timing was poignant, as it was his last starry night with us.
I met him once (almost twice) and he signed my astronomy book I had as a kid. It was a special book, because for me at the time it was a gateway to literally the universe. Pre Internet, and living in a rural backwater with nobody on the same wavelength as me, his book gave me a glimpse that there were people out there who had their minds focused on bigger things.
I studied astronomy at uni for a bit, and he was friends with one of the professors. It was the best bit of my uni course, and though I never did anything more than a first year subsidiary in it, I know it was probably through his book that I got there.
When I met him years later, he was promoting his newest book, about extra terrestrial life on mars. I raised a point about some work by a couple of other scientists who speculated life was spread throughout the universe far more than we realised. He actually was friends with one of these scientists! The connection with cutting edge science was there, and it was real.
So, Patrick Moore is a hero to me, for his life's work and passion for truth.