Some unpleasant people became part of Gatsby's dream. But he cannot be blamed for that. Gatsby was a success, in the end, wasn't he?
Hint (which hopefully you don't need): The answer is not F. Scott Fitzgerald.
UPDATE: Don't all race to give the answer all at once -- but it's Margaret Tarner, who "re-told" the Fitzgerald classic for "intermediate readers" in a travesty that is ripped to shreds in a great blog post from Roger Ebert.