Mageddon is a fictional character that appears in comic books published by DC Comics. The character first appeared in JLA #37 (Jan. 2000) and was created by Grant Morrison and Howard Porter.
Although previously hinted at in several issues of JLA and referenced as being the entity Tezcatlipoca in Aztek: The Ultimate Man #1 (Aug. 1996), Mageddon actually first appeared in the World War III storyline in JLA #37–41 (January–May 2000).
The existence of Mageddon is first revealed to the hero Aztek, who learns that he must eventually face and defeat Tezcatlipoca, the Aztec god of evil. When the JLA thwart the plans of the mysterious "Know-Man", who attempted to give all Earth's population superpowers, he justifies his action as an attempt to prepare Earth for the coming of the "ultimate warbringer". Mageddon's name is first mentioned when JLA members Aquaman, the Flash and Green Lantern visit a planet named Wonderworld, whose super-powered inhabitants, led by Adam One, warn the heroes of the rise of an entity named Mageddon, also referred to as the "anti-sun", which exists beyond the boundaries of the known universe. At the conclusion of the "Rock of Ages" arc, Metron of the New Gods visits Wonderworld and discusses an unnamed threat with Adam One, implying that ultimately it will not be Wonderworld that has to face said threat.