"Civil War" is a 2006–07 Marvel Comics crossover event. The storyline consists of an eponymous seven-issue limited series, written by Mark Millar and penciled by Steve McNiven, and various tie-in books. The storyline builds upon previous Marvel storylines, particularly "Avengers Disassembled", "House of M", and "Decimation". The series' tagline is "Whose Side Are You On?"

Mark Millar is a Scottish comic book writer who first came to prominence with a run on the superhero series The Authority, published by DC Comics' Wildstorm imprint. Millar has written extensively for Marvel Comics, including runs on The Ultimates, which has been called "the comic book of the decade" by Time magazine and described as a major inspiration for the 2012 film The Avengers by its screenwriter Zak Penn, X-Men, Fantastic Four and Avengers for Marvel's Ultimate imprint, as well as Marvel Knights Spider-Man and Wolverine. In 2006, Millar wrote the Civil War mini-series that served as the centrepiece for the eponymous company-wide crossover storyline and later inspired the Marvel Studios film Captain America: Civil War. The "Old Man Logan" storyline, published as part of Millar's run on Wolverine, served as the inspiration for the 2017 film Logan.