The Companions of Jorrvaskr are one of many factions that you can join in Skyrim. Based in Whiterun, they're a group of impressive warriors, so why wouldn't they want to add the famous Dragonborn ...

Most of the followers you're going to find in Skyrim are Nords ... The other races get some representation in the companion roster too, except the reptile Argonians, who seem to have missed ...