i know what you mean, but i'm going to stretch the definition a bit.
I vote for Ron Dawes and my reasoning is this:
The dude never went sub-5 for a mile in high school. He didn't have as much talent as other runners, but he made up for it with smart training and real dedication. He dissected Lydiard's books and applied the knowledge carefully. He ran to work, found ways to train when the weather wouldn't allow it, and trained in multiple layers of clothing to get used to excessive heat.
All of his hard, smart work paid off on the day of a hot marathon trials. He was not a favorite to make top 3, but the accumulation of his dedication - along with a little bit of luck - paid off.
Ron Dawes by all accounts should have never been an olympian, but he f*cking did it. He was a real blue collar runner who didn't make excuses. He got to work and made $hit happen. He was, and still is, an inspiration to me.
a lot of younger runners would do well to follow in his footsteps.