From Action Comics #13 (June 1939). Written by Jerry Siegel; drawn by Joe Shuster.
What begins as a typical story of Superman’s war on a protection racket takes a surprising turn when he learns that there’s a super powered mastermind behind it. The bald man in the wheelchair calls himself the Ultra-Humanite, a play on Superman’s own name, but instead of being super strong, he’s super intelligent.
It looks like the Ultra-Humanite dies at the end in a plane crash, but Siegel and Shuster knew that they’d hit on something special and call attention to Superman’s not finding the villain’s body in the wreckage. “That finishes his plan to control the earth,” Superman says. “Or does it?“