Batman
The first Batman story, "The Case of the Chemical Syndicate", was published in "Detective Comics" #27 (May 1939). Finger said, "Batman was originally written in the style of the pulps", and this influence was evident with Batman showing little remorse over killing or maiming criminals. Batman proved a hit character, and he received his own solo title in 1940 while continuing to star in "Detective Comics". By that time, Detective Comics was the top-selling and most influential publisher in the industry; Batman and the company's other major hero, Superman, were the cornerstones of the company's success. The two characters were featured side-by-side as the stars of "World's Finest Comics", which was originally titled "World's Best Comics" when it debuted in fall 1940. Creators including Jerry Robinson and Dick Sprang also worked on the strips during this period.
Joe Chill
Batman's origin story is first established in a sequence of panels in "Detective Comics" #33 (November 1939) that is later reproduced in the comic book "Batman" #1 (Spring 1940), but the mugger is not given a name until "Batman" #47 (June–July 1948). In that issue, Batman discovers that Joe Chill, the small-time crime boss he is investigating, is none other than the man who killed his parents. Batman confronts him with the knowledge that Chill killed Thomas and Martha Wayne. Chill, believing there is no way Batman could know this, accuses him of bluffing, but Batman reveals his secret identity quoting "I'm the son of the man you murdered. I'm Bruce Wayne." Terrified, Chill flees and seeks protection from his henchmen. Once his henchmen learn that Chill's actions led to the hated Batman's existence, however, they turn on their boss and gun him down before realizing how priceless his knowledge of Batman's true identity is. Before the dying Chill has a chance to reveal Batman's identity, the Dark Knight intervenes and knocks out the goons so they will never hear what Chill has to say. Chill expires in Batman's arms, acknowledging that the Dark Knight got his revenge after all. Len Wein and John Byrne add a one-panel coda in their retelling of this scene in the first issue of "The Untold Legend of the Batman". Batman stands over Chill's body and says "No, Chill -- The Batman didn't finish you... It was Bruce Wayne!"