There are a lot of costumes from beast tribes, the mog station and the market board. You can dress up as a vath, a vanu, a kojin, a dwarf, an arkasodara, a fauth, a namazu, a chocobo, a lupin, a moogle, an ascian, odin or a garlean (sort of). There is also Wyvernskin Mane of Fending.