Detective Comics (1937)

Detective Comics #27, DC, May 1939 Batman's first appearance, and Bob Kane's cover already has the essentials: the bat-eared cowl, the scalloped cape spread like wings, and a rooftop swing with a crook locked under one arm. The issue also introduced Bruce Wayne and Commissioner Gordon. Note how the cover still sells the anthology first, with the title logo dwarfing "The Batman!" in the corner blurb.