Psychopomps are spirits or similar beings who escort the dead to the afterlife, both in Gunnerkrigg Court and in the mythologies of many cultures in the real world. Though usually invisible to the living, mediums (and possibly others) such as Surma have the ability to see and interact with the guides, a trait that her daughter also possesses.
Antimony first encountered the guides as a child while living in Good Hope Hospital. Muut was the first one she ever met. She would join them when they visited dead or dying patients, although she did not initially realize the true nature of their job. Eventually, Annie would come to help them in their duties by acting as a mediator, much as her mother did before her. Now that she lives at Gunnerkrigg Court, Annie still sees the psychopomps from time to time when a death brings one of them to the area.