The Postman is the main antagonist of the first episode of Grimm, a ruthless Blutbaden (werewolf like creature) that preys on others when he gets hungry, and kidnapps them to fatten them up.
He had killed atleast six others as shown by the red coats he kept from his victims. He devoured one young woman while she was out running in the forest, before kidnapping a child with intentions of fattening her up for his next meal. This attracted the the attention of Detective Nick Burhardt, who had recently discovered he was a Grimm (a supernatural warrior whose duty it is to protect people from creatures like the postman) with the help of a reformed Blutbaden named Monroe he managed to track down the postman. Calling his partner Hank they investigated, but senseing them the postmen managed to hide all the evidence of anything being wrong. However as they were leaving, Nicks partner realised that he had been humming the same song the first girl he had eaten was listening to when she died, the two ran back, in the confusion the Postman ran out, but was shot in the back of the head killing him. Nick managed find where he hid his victim and return her to her family.