The Toothy Deer was, essentially, a mascot of ROBLOX. It was seen in ROBLOX's first commercial and was seen all around the site for some time. Eventually, a user created an account called ToothyDeer, and became the 'official' Toothy Deer. 

Recently, however, the ToothyDeer account was compromised by the account owner's brother, and ultimately banned. ROBLOX, we need to unban ToothyDeer. There will never be another username like him.