John Constantine is a fictional character who appears in American comic books published by DC Comics. Constantine first appeared in Swamp Thing #37, and was created by Alan Moore, Steve Bissette, and John Totleben.

The character the Swamp Thing has appeared in seven American comic book series to date, including several specials, and has crossed over into other DC Comics titles. The series found immense popularity upon its 1970s debut and during the mid-late 1980s under Alan Moore, Stephen Bissette, and John Totleben. These eras were met with high critical praise and numerous awards. However, over the years, the Swamp Thing comics have suffered from low sales, which have resulted in numerous series cancellations and revivals.