Corporate rivals Marvel and DC first teamed up in the 70s; an adaptation of The Wizard of Oz was followed by two Superman/Spider-man team-ups. These set the tone for many pairings that followed, by positing that the characters always shared the same universe. Many later crossovers had the characters living in parallel universes, despite the fact that DC and Marvel's house styles have grown more alike since the 1970s.

This 1996 comic began a multi-issue crossover mini-series based on the premise of parallel universes. Fans voted on the outcome of the various super-matches. Later, an assortment of one-shot "Amalgam Universe" characters emerged, who combined features of specific Marvel and DC heroes and villains.

Super-heroes who team-up traditionally fight a pair of villains who have also decided to work together. A mid-1990s pairing of Superman and the Silver Surfer featured Mr. Mxyzptlk and the Impossible Man, who eventually turn on each other and during their battle, mimic a cross-section of characters from their respective universes.

Although DC and Marvel did not officially crossover until 1975, DC unofficially teamed up with their rival in a 1972 Justice League of America.