The Platonians were a humanoid race. They had a very long lifespan. They eventually acquired the ability to psychokinesis. Psychokinesis is the power to move objects by thought.
They were civilized and corteous among each other. They spent much of their time in mediation. The thought of other species as inferior.
They used to live on a planet in the Sahndara star system. They instituted a mass eugenics program to breed for self-reliance and longevity. They managed to escape before the Sahndara went nova.
They traveledto Earth sometime before 400 B.C. They used the Greeks as a model for their society. After the fall of the Greeks, they left Earth and settled on a new planet.
They were first encountered by the crew of the U.S.S. Enterprise in 2268. There was only 38 of them. They were likely to be over 2,500 years old.
Captain James T. Kirk, Commander Spock, and Doctor Leonard McCoy beamed to the planet. They were held captive. They forced Uhura and Nurse Chapel from the Enterprise to beam to the planet. The crew was forced to act like puppets.
Kirk defeated the Platonian, Parmen. The Enterprise crew was able to return to the ship and took a Platonian, Alexander, with them.