I am not a die-hard "Star Wars" fan, but John Williams' "Star Wars" score is as iconic as they get. He's scored all 8 films of the saga and basically made a career out of it, although his 1975 score for Spielberg's "Jaws" is, for my money, is as good as anything ever composed for a "Blockbuster" movie.
He spoke to The Mirror recently and revealed that, shock, he's never seen any of the "Star Wars" movies.
“I let it go. I have not looked at the ‘Star Wars’ films and that’s absolutely true. When I’m finished with a film, I’ve been living with it, we’ve been dubbing it, recording to it, and so on. You walk out of the studio and, ‘Ah, it’s finished,’ Now I don’t have an impulse to go to the theater and look at it. Maybe some people find that weird, or listen to recordings of my music very, very rarely.”
So there you go. It's not the only iconic score he's done. Remember, he has scored practically every Spielberg since "Jaws." I'd say the best work he's done is the following: "Schindler's List," "Jaws," "Raiders of the Lost Ark," "Harry Potter," "E.T," and "Superman."