What Are Hats?
Hats come in many different shapes, colors, and sizes in real life. Sadly, Terraria does not contain too many solo head vanities. This idea was created to change that.
Mobs like Doctor Bones and Rune Wizards drop their 'clothes.' But not many other mobs so that, though they should. To fix that, there should be new items called 'Hats' which can spawn on any mob at any time. These 'hats' can be found both in prehardmode and hardmode, and, unlike the hat of Doctor Bones, can be found on any mob.
How Many Hats Are There, and What Are They?
Each hat is pretty rare to find on a mob, but with more than 30 hats, it is not uncommon to see a monster wearing one. Some hats include:
Stove Pipe Hat
Please Keep In Mind That These are Only A Few Hats, and More Will Be Added To This Thread Soon. Thanks @BryTheGamer for sprites!