Trelane was a powerful, childish being who captured the Enterprise crew on the planet Gothos and treated them as playthings until his parents stopped him.
Trelane was a being of great power who lived on a rogue planet he called Gothos. He was fascinated by Earth, which he had studied from afar, and dressed and spoke like a squire of an earlier century, though his knowledge was out of date because the light he observed from Earth was hundreds of years old.
In the original series, Trelane snatched Kirk and Sulu from the bridge of the Enterprise and then held a landing party in his strange castle. He played the gracious host, threw a formal party and staged a mock trial and a duel, but grew dangerous whenever his games were refused. Kirk finally challenged him to a hunt, and just as Trelane was about to win, his parents, appearing only as glowing lights and voices, called him home, scolded him and apologized to the crew for his behaviour.
Trelane's mix of great power and childish behavior made him a forerunner of later all-powerful beings such as Q, and he remains one of the most memorable guest characters of the original series.