William Barrow is a minor antagonist in Season 3(b) of Teen Wolf. He is a serial killer and convicted mass murderer. He is portrayed by Doug Jones.
Born May 24, 1960, William Barrow, also known as The Shrapnel Bomber, is an electrical engineer. He is undergoing surgery to remove a tumor. In the pre-op interview, he tells Melissa McCall that he killed the kids he did because they had glowing eyes.
The tumor turns out to be filled with flies. Barrow escapes the hospital and goes straight for the school, where he patches himself up with a staple gun in Coach Finstock's office.
It then turns out that he's after Kira. He follows her to the library, but Finstock unwittingly saves her. Barrow later finds the Kitsune, Kira at her house. He knocks Scott out with a tire iron and brings Kira to a power substation. He then takes a photo of her with her phone in order to prove that her eyes glow and then he touches her with an electrical main. The substation then explodes, and he appears to die from electrocution.
It is implied that the Nogitsune possessed him to kill the kids on the bus.