Spirit Warriors

This is a radical activist group that has grown out of the American Indian movement (AIM, but not to be confused with the hopefully-defunct villain organization of the same initials). They tend to show up wherever Amerindian rights are being violated, or perceived to be being violated and take the most destructive possible action. Leadership tends to switch from one leader to another, but the most prominent enforcer (when he's not in jail) is Bearwalker, a shapeshifting werebear with immense strength and durability.