This Katy Perry foto contains
porkpie, porkpie hat, and porkpie hoed.
There might also be
snap rand hoed, module rand hoed, fedora, vilten hoed, homburg, cowboyhoed, trilby, fedora met vilten hoed, stetson, schipper, leghorn, panama, hoed, zeeman, skimmer, strooien hoed, livorno, panama hoed, matroos, and stro hoed.