The actor that I'm looking for was in one episode, played a very energetic fellow whose actual first name is Bruce and who subsequently joined the Swami Order in Los Angeles. Thanks so much!
His name was Bruce Mars, but now he is known as Brother Paramananda, according to the LA Times.
When Brother Paramananda of the Self-Realization Fellowship stepped away from the Material World, he was a young actor named Bruce Mars. Among his roles: a "Star Trek" space cadet whose latent aggression is unleashed on a planet where all subconscious desires come to life, allowing him to terrorize Capt. Kirk.
The whole article is here
Actor is Bruce Mars. He was in three trek episodes. The most famous (and the one you're probably thinking of) is 'Shore Leave' where he played the character Finnegan. According to IMDB, he was also in Assignment Earth as the first policeman and in The Corbomite Maneuver as Crewman #1 (uncredited).