Originally introduced in the comic Amazing Spider-Man #25, Mary Jane Watson (also known as M.J.) is a frequently recurring character in the Spider-Man universe. Watson was originally created to be a temporary love interest for Peter Parker (aka Spider-Man), only to end up replacing Gwen Stacy as his primary love interest as the comics progressed. Watson has gone on to become a mainstay of the series, appearing in the vast majority of Spider-Man works, often as a main character.
In most Spider-Man media, she tends to work as a model/actress, and often finds herself in cliched position of "Damsel in Distress". However, later Spider-Man works also portray her as a night club owner, an assistant to Tony Stark, a band member of Gwen Stacy's, and an investigative reporter. Watson also often takes the role of Spider-Woman, first filling the role in the Exiles series of comics, where she works with the Avengers alongside dating Mariko Yoshida, the Exiles version of Sunfire.