Actaeon
Actaeon moved away from the clearing feeling different and confused, not yet realizing what had happened to him. The truth hit him when he saw his own reflection in a river and he knew he was no longer human. In the distance he heard the sound of his own hounds. A brief moment of joy quickly turned into fear when he realized they were hunting him now, not recognizing their former master. He fled but was eventually overrun and torn to pieces.
A different version of the myth tells that Artemis turned him into a stag because he boasted of excelling her in hunting. (Ovid III, 193)