The first appearences of hats and hair came on a blog post of May 3rd, 2007. Mike Rayhawk, also known as Brickmason, was one of the concept artists who contributed art on badges, Robloxian body concepts, webpage concepts, and even the original Roblox logo. He often worked on Lego, but was hired by Roblox to help come up with concepts for Robloxians between 2004 and 2006. In 2007, John Shedletsky recreated one of the concept arts, which is where the FusedGirl model comes in. The first tease of this was a very low polygon hair piece seen on a Robloxian within the May 3rd 2007 blog. On May 8th, the concept art was shown on the blog, but was ultimately scrapped. The hairpiece remained a part of the original fusedgirl mesh model and wasn't seperated like it was shown previously. So, this hairpiece was never used.
However, it is widely believed and accepted that this hairpiece isn't actually the first recorded hat. The first hat that was made for Robloxians was a blank, textureless Top Hat made by Erik Cassel, within the same May 3rd Blog post. Later, when the first batch of hats would release, it was shown that this hat was the Purple Banded Top Hat. However, Shedletsky later revealed that the original version of it was blue, meaning the first Roblox hat was likely a blue banded top hat, that was later recolored to purple. Many early roblox hats have textures very clearly created in paint, or borrow textures from websites at the time. It wasn't until May 30th that hats would begin to release. While the top hat can technically be considered the first hat (if we are ignoring the scrapped hair piece), the first hat RELEASED on the catalog is actually the Red Baseball cap. Many hats at this time were released with mockup prices and would have their prices fluxuate and change as time progressed, to balance out the catalog and view statistics. So. Prices will not be shown for these items. Only their release dates. Many of the hat creators near this time period were either made by Gamer3D, Erik, Cruss Kilderstrohe, Clockwork, Shedletsky, or Stoecker, as they would often upload the items to their profiles for testing. Many of the hats at the time were called 'headgear', and were made using ZModeler. May 3rd
The ideas thought up by Gamer3D and Shedletsky include "a Crown, Ninja headgear, Pirate hat, World War I helmet with spike on top, Police cap, Fireman's helmet, Racing helmet (suggested by Are92), Spaceman helmet, Midieval helmets - lots of different kinds, Cowboy hat, Baseball cap, Sailor hat, Top hat, Chicken head hat, Wizard hat, Witch hat, Shako, Beret, Robin Hood cap with feather, Hood or cowl, Alien antennae, and a Princess hat
By this point, you can tell which hats are being thought up. Some of these would not release for a while.
Gamer3D, Erik, Shedletsky, and apparently Cruss Kilderstrohe (for future items) are known to be working on hats at this point.
Many hats that are suggested by users include Mario-themed or Halo-themed hats, and flaming hair.