The Debut Of Robin, Sensational Character Find Of 1940
In Detective Comics #27, when he first appears courtesy of Bill Finger and Bob Kane, Batman isn't really Batman just yet. He's the Shadow with a different set of clothes. Over the course of that first year, you can see the pieces start to fall into place that would stay there for the next seven decades, forming the foundation of the Batman that we still have today --- and in Detective Comics #38, released March 5th 1940, the final piece of the puzzle appears when we're introduced to Dick Grayson, better known as Robin, the Boy Wonder.