Batman Hangs a Mental Patient from the Batplane (Batman No. 1, 1940)
Batman's career in needless, brutal murder started early. In the very first issue of Batman's solo rag, an evil scientist uses a toxic serum to turn a group of innocent mental patients into muscular, out-of-control monsters. The scientist's henchmen are driving one of the monsters to town, planning to set it loose in front of a bank they want to rob. Unfortunately for them, Batman had just finished mounting a brand spanking new machine gun onto the Batplane.
"Rat-tat-tat-tat-tat-tat-tat-tat ... Batman!"
Batman guns down the driver and causes the truck to crash into a tree, but the henchmen actually get off easy compared to what's about to happen to the confused, mentally handicapped mass of muscles in the back: As soon as he falls out of the truck, and before he can hurt a single soul, Batman drops a noose made from reinforced steel and easily snatches the monster by the neck:
He'd been practicing this very maneuver on vagrants for months.
Batman then lifts off the aircraft as the monster desperately struggles to break free from the noose, choking him to death and thus performing the world's first execution by bat-shaped plane. The Batplane then sails smoothly toward its next destination with a few hundred extra pounds of genetically altered dead weight attached, swinging like a grotesque pendulum.
Most people just hang fuzzy dice on the mirror, but whatever.