Come on, at least use the name people know Sameul by...Samuel WANJIRU. But I didn't know him nor ever hear an interview with him, so he cannot be my pick (I did love watching him run though!)
First person that came to mind is Lance Armstrong. No, I don't personally know him either, but I've been cycling for 20+ years and have followed him very closely. I think he is driven, is talented and focused, but yea, he hasn't always been the nicest person (and that's putting it mildly).
At the moment, there is no one else "famous" that I am familiar enough with because I just don't care enough to follow pop culture.
It says something that no runner comes to mind...because most of them seem to have the personalities of a piece of paper. Just blank and boring.
Nick Symmonds seems pretty cool, and at this point, I don't know that he has any flaws worth pointing out. He's doing a nice job trying to popularize running on his YouTube channel (along with his company and himself, but that is fine).