This Prince William and Kate Middleton photo contains
fedora, felt hat, homburg, stetson, trilby, boater, leghorn, panama, panama hat, sailor, skimmer, straw hat, and business suit.
There might also be
campaign hat, dress hat, high hat, opera hat, silk hat, stovepipe, top hat, topper, beaver, pith hat, pith helmet, sun helmet, topee, and topi.