10 Times Marvel And DC Secretly Crossed Over
4. The Avengers And Justice League Sort Of Fought Each Other
Long before the Crusaders, Avengers writer Roy Thomas and Justice League writer Denny O'Neil had a similar idea to have their two teams fight each other.
In Avengers #70, the team fought the Squadron Sinister. The Squadron consisted of evil versions of the Justice League like Hyperion (Superman), Nighthawk (Batman), Dr. Spectrum (Green Lantern) and Whizzer (Flash).
The plan was that the Justice League would fight an evil version of the Avengers at the same time, but (probably thanks to DC's stricter editorial team) the plan unfortunately fell through and Justice League America #75 instead featured the League fighting evil versions of themselves.
However, Thomas managed to get his crossover a little over a year later with Mike Friedrich. In Avengers #85, the team travelled to an alternate world where they fought a new and more heroic version of the Squadron called the Squadron Supreme.
Meanwhile, in Justice League of America #87, DC's greatest heroes fought the Heroes of Angor. The Heroes were also from an alternate universe and consisted of the Australian wind god Wandjina (Thor), Jack B. Quick (Quicksilver), Silver Sorceress (Scarlet Witch) and the size-changing Blue Jay (Yellowjacket).
The Squadron Supreme have since become pretty prominent members of the Marvel Universe. Most of the Heroes of Angor were killed off though, except for Blue Jay who joined the Justice League for a while.