#5 Cancer Fish
Jimmy Phishetti is a local mob boss. His leadership of the family is undisputed due to his supernatural powers.
He has the ability to cure cancer patients, such as Heartstrings, absorbing the cancer cells into his own body. Depending on how much cancer he has recently consumed, he has the potential to be many times stronger than a normal human being, and is nearly unkillable.
Unfortunately some of the side effects of having that much cancer in his body have not been so beneficial. He has developed gills on his neck, and if he does not submerge himself at least once a day, he will die.
He uses his curative skills to draft soldiers into his army, offering them a clean bill of health in exchange for 5 years of devoted service.
Truth told, I came up with the Cancer Fish idea completely by accident. I was playing City of Heroes and decided to make a villain character based on this character from my webcomic, Jimmy and the Hammer. Unfortunately, the name I wanted (revealed here, spoilers!) was taken, the costume looked almost entirely different than the original (pretty much a generic read suit with fish fins on the wrists) and he inexplicably had radioactive powers. Thus I named him Cancer Fish instead, and the rest grew with time.
That is a freaking bizarre superpower. Well done.