In the spring of 1940, Bob Kane, Bill Finger, and Jerry Robinson created the first superhero sidekick, the original supervillain, and the bad girl criminal who would forever cross the hero's path. By adding Robin, the Joker, and Catwoman, the creators not only expanded Batman's cast but broadly changed comic books forever. Why did they make such an impact? Why have they endured? Were these characters so successful simply because each was the first of its kind? Travis Langley (Batman and Psychology: A Dark and Stormy Knight), Will Brooker (Batman Unmasked), Greg Capullo (Batman), Danny Fingeroth (Superman on the Couch), Gerard Jones (Men of Tomorrow), Lee Meriwether (Batman: The Movie), David Uslan (The Rise of Superheroes and Their Impact on Pop Culture), and E. Paul Zehr (Becoming Batman) take a look at why Kane, Finger, and Robinson created each of these characters, evaluating these creations with regard to the Zeitgeist for 1940, the repercussions of the Comics Code Authority, and the fluctuating standards over time. Changes in these characters reflect the specific changes that defined the Golden Age, Silver Age, Bronze Age, and later comic book eras.