This is more of an idea that fizzled out than a story, but one of my big disappointments was Bill Mantlo's Derangers.
Back in the 80s an issue of Amazing Heroes featured an article on four new series Mantlo was to be writing: Cloak & Dagger, Rocket Raccoon, Swords of the Swashbucklers, and The Derangers. Only the first three saw light of day as originally intended.
I no longer have the issue so I'm going on memory, but it was about a group of individuals with various mental illnesses (it might not be so acceptable today), whose powers reflected those illnesses. For instance there was a housewife named Breakdown who could literally explode and reform. There was a burned-out rock-star who was basically a tank, and I think a character based on multiple personalities. Maybe some others I forget. They were under the guidance, or perhaps mis-guidance of their psychologist, Doctor Bedlam.
The series was to be drawn by Butch Guice.
For whatever reason, it never happened. I waited, and waited... until finally they appeared as a bunch of generic villains in Alpha Flight. With the exception of Goblyn, a young girl with a demonic "imaginary" friend, none of them were explored or given any depth.
And the art wasn't as good.