This Doctor Who screencap contains
fedora, felt hat, homburg, stetson, trilby, boater, leghorn, panama, panama hat, sailor, skimmer, and straw hat.
There might also be
porkpie, porkpie hat, business suit, dress hat, high hat, opera hat, silk hat, stovepipe, top hat, topper, and beaver.
Paul McGann has spoken about returning for The Night of the Doctor and gave some thoughts on the regeneration limit now that another one has been used up.