Well, he might only be a celebrity to me, but walking home from work today I saw Harry Mathews. It was the corner of Sixth Avenue and 11th Street (near the New School Lang Building) and he was carrying a newspaper. I recognized him because I saw him read at DU in 1996, and he has a distinctive face. I should have stopped and said, "Whoa! Harry Mathews, famous American writer! I can't believe it!" but I didn't want to freak him out. I imagine he only rarely gets recognized by perfect strangers. Well, maybe if I see him again, I will tell him I am a fan. He might be flattered.
A decent bio is here. Mathews is the only American in the Oulipo group. I highly recommend book "The Journalist."