Forgot Jerry Lewis, The Nutty Professor.
There must be a few other titles I didn't think of.
The Coens are a special case, I like their comedies, so to speak, as long as they're not trying to make a comedy. I think Fargo and The Big lebowski are genuinely funny, but they aren't real comedies; on the other hand I find some of their movies that were certainly meant to be comedies (notably Raising Arizona and The Hudsucker Proxy) particularly awful.
Fellini did a few better movies (Otto e Mezzo in particular), but Amarcord is his funniest movie, the closest he got to genuine comedy.
Play Time by Tati is a wonderful piece of film making, but I can hardly see it as a comedy either.
But this is probably the same discussion as the one we had in relation to westerns: when is a movie a western and when is a western no longer a western?