Gorgan is an antagonist who was first introduced in the Star Trek episode "And the Children Shall Lead".
He was portrayed by the late Melvin Belli.
Millions of years ago, Gorgan, the Beta XII-A entity, The One, and 0, had joined together to sow chaos throughout the galaxy after Q had given 0 access to the prime universe through the Guardian of Forever. The group was responsible for a number of atrocities, including the destruction of the T'Kon Empire. Gorgan had provoked some of the colony worlds of the T'Kon Empire into a civil war with the home star system.
Due to the actions of Gorgan and his friends, the other members of the Q Continuum confronted Gorgan and his friends in battle. Gorgan eventually ran from the battle and hid himself in a cave on Triacus. When an expedition from the Federation arrived on Triacus in the mid 23rd century, Gorgan manipulated the adults into committing mass suicide.
Gorgan then used the children in an attempt to conquer the galaxy. When the Enterprise arrived to determine what had happened to the expedition, Gorgan accompanied the children as the Enterprise departed the system. He was briefly able to seize control of the Enterprise before Kirk made the children realize that Gorgan was a monster who was using them for his own purposes. The children and Enterprise crew saw Gorgan as he truly was. Realizing that he had been exposed, Gorgan fled the Enterprise.