Superman was created by two nineteen-year-olds from Cleveland, Jerry Siegel and Joe Shuster. An amalgam of pulp-magazine science fiction and comic-book fantasy, the Man of Steel was the first superhero. For a long time he was also the most popular — even with competition from a plethora of costumed crime fighters introduced in the late 1930s and early 1940s. Next in popularity was Batman, created by Bob Kane and Bill Finger, who were influenced from even more directions: pulp-magazine figures such as the Shadow and Doc Savage; radio crime fighters such as the Green Hornet and the Lone Ranger; Zorro and gangsters from the movies; and comic-strip characters such as the Phantom. Superheroes quickly fell into two camps: either they were like Superman in exhibiting unusual abilities, soon labeled superpowers, or they were "normal" men (and occasionally women) who fought crime, like...