Ace Comics #11 (1938) is widely recognized as the first comic-book appearance of The Phantom, created by legendary writer Lee Falk. The character introduced the idea of a masked, crime-fighting hero whose identity and legacy were passed down through generations. The Phantom became a hugely influential figure in comics history and is often regarded as one of the earliest true hero characters, helping establish the template for many costumed heroes that followed.  The comics is available for purchase below.