Superman had a childhood rival he never mentioned or even seemed to know about back in the 90s.
The Clone Saga had a villain so mysterious, even his creators didn’t know what his deal was.
A group of criminals gain powers, but only when they’re chained together.
Plenty of Silver Age heroes had sidekicks. Few were as weird as Zook.
Captain America once dated a reformed supervillain.
A Golden Age legacy goes into action if she can keep her mouth shut.
An animated supporting character becomes a superhero in print.
The original Batgirl is a bit of a mystery in certain ways as a Silver Age hold-over.
Wonder Woman had a temporary replacement once. It did not go well.
The Ultraverse had its own muck monster.