Billy the Axeman - unknown serial killer responsible for a series of family murders along train routes in the early 1900s.

How the hell do you bash someones head in with an axe without making enough noise to wake anyone else in the house? Especially when it's a couple, like how do you not immediately wake up when the person sleeping right next to you gets their skull caved in?

I grew up next to a railroad crossing so I can sleep through train horns but I doubt even I could sleep through that.

Subject of The Man from the Train.