This MJ's This is it photo contains
fedora, felt hat, homburg, stetson, trilby, porkpie, porkpie hat, and campaign hat.
There might also be
snap brim hat, boater, leghorn, panama, panama hat, sailor, skimmer, straw hat, dress hat, high hat, opera hat, silk hat, stovepipe, top hat, topper, and beaver.