The 1930s also witnessed the development of popular literary genres. Pulp fiction magazines began to feature distinctive, gritty, adventure heroes that combined elements of hard-boiled detective fiction and the fantastic adventures of the earlier pulp novels. Two particularly noteworthy characters introduced were Doc Savage and The Shadow, who would later influence the creation of characters such as Superman and Batman. Near the end of the decade, two of the world’s most iconic superheroes and recognizable fictional characters, Superman and Batman, were introduced in comic books.