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.
Detective Comics
Batman's origin is first revealed in a two-page story in issue #33 (Nov. 1939). Batman became the main cover feature of the title beginning with issue #35 (Jan. 1940). Issue #38 (April 1940) introduced Batman's sidekick Robin, billed as "The Sensational Character Find of 1940" on the cover and the first of several characters that would make up the "Batman Family". Robin's appearance and the subsequent increase in sales of the book soon led to the trend of superheroes and young sidekicks that characterize the era fans and historians call the Golden Age of Comic Books. Several of Batman's best known villains debuted in the pages of "Detective Comics" during this era including the Penguin in issue #58, Two-Face in issue #66, and the Riddler in issue #140.