The dead and undead are tied to a variety of different magic types. The souls of the deceased are of particular interest to the Aracanas of the Papess Throne and the Bone Hollows, the Priestess and Death. Ghosts can arise naturally and magical practitioners can summon the undead. Bless-fire acts as a purifying force that can be used against the them, while spells such as the Soul-bind release trapped souls.
Certain areas draw the dead, especially locations of past trauma and negative psychic energy, as well as sites that have been warped by magic. In New Atlantis, such haunted places include Farstryke Castle and Sun Estate.
In New Atlantis, Rune witnesses gray and translucent impressions of people and things flickering in and out of visibility, although these are not ghosts. At New Saints Hospital, patients, staff, and physical details from the building's past fade in and out. The events surrounding ships' destruction appear around the boats of the Green Docks. Usually these impressions can be seen by adjusting one's magical sight, although those at New Saints are more easily visible. These residual imprints do not interact with people and things in the present.
Types of Spirits and Undead
Ghosts and haunts
Ghosts and haunts can interact with things and people. Daytime haunts are usually weak, translucent ghosts that do not have a physical presence and are mostly harmless.
Spectres, though insubstantial, are savage day-walking ghosts that can be summoned. Their appearance is smoky and man-shaped. They physically damage their victims, ripping flesh and coating it in frost. Concentrated fire and bless-fire destroy spectres. 
Go-ryos, however, move during the day and consist of skeletal parts from a noble house's mass murder victims. Not dangerous, they instead continuously travel between the death sites of the people making up the skeletal parts. The souls of the deceased can be put to rest with a Soul-bind spell, at which point in time the skeletal composite disintegrates.
Wraiths are particularly dangerous and hungry ghosts; they eat living things as well as the flesh of revenants. Wraiths shed memories when destroyed, and those memories can be experienced by the living.
Los desmembrados is a manifestation made from the spirits of multiple accident victims. They draw physical matter together to construct a humanoid body out of parts, such as gems or metal fragments. Difficult to kill, they can repair themselves and regenerate their physical bodies. Originally local to Puerto Rico, they spread with Puerto Rican emigrant communities. Most desmembrados have no sentience, although a particularly powerful example in the translocated Worcester Galleria combines the death emotions of several spirits, is able to split itself into smaller entities, and uses the death phrases of its component spirits to communicate.
Ghouls: Meat and blood attract ghouls, which can be distracted by 'flesh-bombs,' balloons filled with blood and fat.
Poltergeists are described as particularly aggressive spirits.
Decomposing corpses, wights continue to exist indefinitely, provided they feed on living creatures. Blood acts to reverse the wight's decay. They often congregate, but can be destroyed through physical attacks.
Revenants are undead bodies summoned and directed by a magic worker. They cannot speak or work magic, nor do they have fully formed personalities, just personality echoes. They fall into at least two types:
Skeletons: Easy to raise in large numbers, they use weapons such as knives. They are generally weak and can can be physically destroyed using spells such as Shatter.
Fleshed revenants: These summoned bodies include the rotten soft tissue of the deceased and retain the skills the body possessed in life. In addition to purifying magic, they can be destroyed by piercing the brain stem. Special scents protect the wearers from revenants.
Liches: Although liches have sentience and willpower, and are a different sort of magical entity, they do share some features with revenants, as they are summoned by magic users and occupy decomposing bodies.