This Selena Gomez 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
porkpie, porkpie hat, campaign hat, and snap brim hat.