John was a deceased individual who was once friends with Saul Ramon.
In 2259, Ramon reported in his personal log that "I swear I saw John standing in the mess hall, like he never… Like he was still alive. And I tried to say something to him, and everyone just stared at me." In reality, the vision of John was created by the extradimensional lifeforms living in the Bannon's Nebula, as they attempted to communicate with Ramon. (SNW: "Lost in Translation")