Described by the narrator as a “dark, sallow man, with a dark beard and rather heavy eyebrows” (313), the signal man initially seems to mirror the dark and clammy conditions in which he works. The protagonist and tragic hero of the story, the signal man is a sympathetic character who has ended up with an underground job as the result of squandering educational opportunities. Nonetheless, the signal man is a reflective man who acknowledges both his past failings and current responsibilities: “He had no complaint to offer about that. He had made his bed, and he lay upon it” (314). He performs his job with “exactness and watchfulness” (314), breaking off conversation with the narrator when he must respond to telegraphs or signal to a train driver, and “remaining silent until what he had to do was done” (315). The narrator concludes, after watching the signal man at work, that he is “remarkably” punctilious about his duties.

However, it is this very acute attention to his responsibilities that torments the signal man in the wake of the third appearance of a ghost near the tunnel. The torture does not lie in the appearance of the ghost itself, but in the warning signals that the ghost gives.