Contagion is the name of a story arc that ran through the various Batman comic book series. It concerns the outbreak of a lethal disease in Gotham City, and Batman's attempts to combat it. The events of this story led into Batman: Legacy and Batman: Cataclysm, which itself leads into Batman: No Man's Land. It ran from March through April 1996.

Gotham City, or simply Gotham, is a fictional city in the Eastern United States that serves as the primary city appearing in American comic books published by DC Comics. It is best known as the home of the superhero, Batman, and his allies and foes. Created by writer Bill Finger and artist Bob Kane, the city was first identified as Batman's place of residence in Batman #4 and has since been the primary setting for stories featuring the character. In most of its incarnations, Gotham is depicted as one of the most crime-ridden cities in the world.