- For other uses, see Barry.
- See St. John for other articles with titles that contain, either by relationship or by coincidence, this character's surname.
St. John accompanied Admiral James T. Kirk, Dr. Christine Chapel, Lieutenant Lex Nakashima, and two other security people, Sergeant Juan Aragonés and Marta Bergstresser, on a landing party to Charlotte, one of the three moons of the planet Cathy in the Novak system. They explored a cave system containing one-third of the lost treasure of Vulcan. According to some accounts, they made first contact with a primitive species called the Teela who inhabited the caves. Also in some accounts, St. John disappeared after a battle with the Teela and was never seen again. According to other accounts, he was found unconscious in a rock crevice and sent back to the Enterprise for treatment. (TOS novella: The Vulcan Treasure)
St. John's disappearance appears to be an error on the author's part due to the complexities of the book's "plot-your-own" format.