Captain America used to be a freelance artist.
Back when Steve still had a secret identity, he worked as an illustrator, even had jobs with comic books. He managed to get the job as both artist and writer of the "Captain America" series, and people told him that the series had never been better after he took over.
Eat your heart out, Peter Parker!
Big Barda used to be a professional wrestler.
Yeah, that was weird.
And it took her a while to get that wrestling is fake... much to the other wrestlers' dismay.
Superman is the adopted father of General Zod's son.
While imprisoned inside the Phantom Zone, General Zod and his mate, Ursa, gave birth to a child they named Lor-Zod. Zod managed to use Phantom Zone technology to created a small space-worthy vessel that could maintain a substantial form and leave the Phantom Zone. As his son was the only Phantom Zoner capable of maintaining a physical form, Zod sent the rocket ship out of the Phantom Zone carrying the boy. The rocket landed on Earth and was found by Superman who pulled some strings and called in some favors so Clark and Lois could adopt the boy as their foster child. They named him Christopher Kent.
Iron Man gave up his sobriety in order to save the world.
During the series "Fear Itself", when a evil Norse god was about to end the world, Iron Man needed help from Odin. Knowing that gods needed sacrifices before giving a damn about a mere mortal's wants and needs.
So Tony gave up his sobriety in order to get Odin's attention.
Black Canary almost married Ras Al Ghul.