Plastic Man [Patrick "Eel" O'Brian]; Chubby Rankin [aka "The Man With the Stealing Hands"](villain)
Chubby Rankin was cursed by an Indian prince and his hands became capable of detaching themselves from their owner's body. He couldn't stop them from stealing, and eventually cut them off. Eventually, Plas threw them into a furnace to set the man free.
In his lab, Roy Lincoln, partly clad as the Human Bomb, paces up and down...
The Human Bomb [Roy Lincoln]; Jean Adams [formerly Jean Caldwell]; The Black Vanguards (villains, introduction for all)
Impatient with Roy's frequent disappearances, Jean nearly sees his face when he changes into the Human Bomb to battle the Black Vanguards, a Nazi group, that is brought down, not by the use of 27-QRX, but a standalone chemical.
Mike Kooiman and Jim Amash state in the Quality Companion that Gustavson created the strip and wrote it. Gustavson's son, Terry Gustafson, concurs.
Letters credit from Terry Gustafson, Paul Gustavson's son.