People who can change form from human to animal. The animal usually has something to do with their heritage and predisposition.
The Jekyl and Hyde Affect Edit
Though the transformation itself is triggered by strong emotions, the disposition of the beast is determined by the disposition of the human. If a shapeshifter is docile, controlled, or overly proper as a human, the beast will be viscous. If a shapeshifter is ravenous or lude as a human, it is docile and sweet in beast form.
Most tribal cultures where shifting is common, they have discovered a means of balance that mainly consists of giving in to impulses without giving in to one's primal nature.