Katherine

Katherine, better know as Kat, is the girlfriend of Gavin.

Kat is in the asylum, after having been taken there on a "date" by  Gavin. Sam and Dean find her when she and Gavin are separated, and despite being scared, she insists on helping find Gavin. Sam and Dean split up and Kat goes with Dean. She gets trapped in a room with a ghost, which Sam works out is trying to communicate with her, not hurt her. It whispers "One thirty-seven" to her, which the boys deduce is a room number.

While Dean goes to find the room, Sam tries to lead the kids out, but finds they are trapped. He leaves Kat with a shotgun to protect them, and responds to a phone call he thinks is from Dean.

Kat and Gavin are safely escorted from the asylum after Dean salts and burns Dr. Ellicott's corpse.