Mega-City One is a fictional city that features in the Judge Dredd comic book series and related media. A post-nuclear megalopolis covering much of what is now the Eastern United States and some of Canada, the city's exact geography depends on the writer and artist working the story. From its first appearance it has been associated with New York City's urban sprawl; originally presented as a future New York, it was retconned as the centre of a "Mega-City One" in the third issue.

Judge Joseph Dredd is a fictional character created by writer John Wagner and artist Carlos Ezquerra. He first appeared in the second issue of 2000 AD (1977), which is a British weekly anthology comic. He is the magazine's longest-running character, and in 1990 he got his own title, the Judge Dredd Megazine. He also appears in a number of film and video game adaptations.