10 DC Comics Stories That Changed Everything
9. All-Star Comics #3 (1940)
All-Star Comics #3 contains the origin of the worlds first superhero team, the Justice Society of America. The formation of the JSA was pivotal not only for inspiring their more popular modern counterpart the Justice League, but for creating the concept of a shared comic book universe.
Before this title, most of the characters on the roster existed completely separate from each other. The seemingly obvious idea of putting a bunch of popular superheroes together in a single narrative had never been attempted before. Not only were these characters meeting for the first time, technically this was a cross company endeavor as All-American Comics and National comics hadn't yet merged to create DC.
The original roster consisted of Doctor Fate, Hourman, the Spectre, the Sandman, the Atom, the Flash, Green Lantern, and Hawkman with Wonder Woman being introduced in the original arcs 6th issue.
The way the arc was structured, each hero would star in their own feature but they were all working toward a common goal, usually coming together in the end. Superman and Batman were also members but enjoyed a "reserve" status. The was due to an interesting editorial policy mandating that any hero currently starring in their own book couldn't be active members.
This policy began the trend of teams having an ever-changing roster with heroes being removed and added. This was also the reason for Wonder Woman's seemingly sexist role as team secretary... doesn't make it feel any less wrong though.