Humanoids of Zalkon, some of whom were evolving into beings of pure energy, a change their government tried to suppress.
The Zalkonians are a humanoid species from the planet Zalkon. Some members of their species had begun transforming into beings of pure energy, and their government saw the change as a threat to its authority and hunted down those affected.
In Transfigurations, the Enterprise rescued an injured Zalkonian from a crashed escape pod. Suffering from amnesia and called John Doe, he healed with remarkable speed and gradually transformed while aboard the ship. The Zalkonian official Sunad pursued him and demanded his surrender, but John Doe completed his evolution into an energy being and departed.