This Michael Jackson photo contains
fedora, felt hat, homburg, stetson, trilby, boater, leghorn, panama, panama hat, sailor, skimmer, straw hat, dress hat, high hat, opera hat, silk hat, stovepipe, top hat, topper, and beaver.
There might also be
snap brim hat, pith hat, pith helmet, sun helmet, topee, topi, cavalier hat, and slouch hat.