Myth Hunters is a Red Dead Redemption posse.
About the posse
Myth Hunters is a group of people very interested in the mysteries in Red Dead Redemption. This started at reddead.net where the X-Files thread is. There people have posted many interesting things, and myth in RDR were born. For a while people who wanted to learn more about these things just had to wait to see if someone posted something about it in the X-Files thread, but not anymore. Now, there is a site AND posse for it. There are no requirements to joining besides wanting a Myth Hunting community.