Krotan is actually a metamorphing bioweapon giving the ability to the user to shape-shift himself. It comes in the form of a drug from Thanagar that allows a person to change himself into any shape or animal he wants. However, it only works once on a human, but a Thanagarian can change their shape an unlimited amount of times. It is highly addictive and prolonged users become incapable of retaining a cohesive shape if not given the drug regularly. Used and trafficked to Earth by the Thanagarian criminal Byth. Introduced in the pages of Hawkworld. Pre-Crisis, Krotan was the name of a scientist who invented a similar drug called the Changeling Pill.