10 Times Marvel And DC Secretly Crossed Over
10. The Crusaders
During the 1970's, both Marvel and DC had comics featuring teams of superheroes from WWII. Over at Marvel, Captain America and Bucky teamed up with Namor, the original Human Torch and his sidekick Toro to form the Invaders. DC had a similar team called the Freedom Fighters, who were led by the ultra-patriotic Uncle Sam.
This similarity didn't go unnoticed by the writers of each series, who decided it would be fun if the two teams met. Since that wasn't a possibility though, they had to come up with a pretty ingenious solution.
In the March 1977 issues of their comics, both the Invaders and the Freedom Fighters fought a team called the Crusaders. The DC team consisted of the shield-wielding Americommando, his sidekick Rusty (who even looked almost exactly like Bucky), the aquatic Barracuda, Fireball and his sidekick Sparky. Meanwhile, the Marvel team was led by the ultra-patriotic Spirit of '76 and included obvious homages to the rest of the Freedom Fighters.
Both teams only lasted for this one "crossover" before disbanding. Americommando and Barracuda have both made appearances in other DC series though and, over on Marvel's side, Spirit of '76 briefly took up the mantle of Captain America when the original went missing.