Spirit

Uther Pendragon in the Spirit World.

“I sensed something, like there was someone there, watching me.”

— Percival to Gaius and Merlin^[src]

Spirits are apparitions of the deceased that can appear to, interact with, and possess the living. Most of the spirits that appear in the series are human, but places and elements can also have spirits associated with them.

Becoming a Spirit

Freya fulfills her promise to Merlin.

Humans (both magical and non-magical) appear to become spirits automatically after death. Most spirits seem to reside exclusively in the Spirit World, but they are capable of existing outside of it (The Coming of Arthur, A Herald of the New Age, The Death Song of Uther Pendragon).

The spirits of sorcerers are unable or unwilling to enter the Spirit World after death, in most cases because they have unfinished business among the living. Freya, for example, became the spirit of the Lake of Avalon in order to fulfill her dying promise to Merlin (The Coming of Arthur). Similarly, the Shrine Boy was unable to find peace until he had forgiven or avenged his death (A Herald of the New Age).

The spirits of non-magical people are also able to exist outside the Spirit World, though they can only exit it with the help of spells, necromancy, or magical objects such as the Horn of Cathbhadh (The Sins of the Father, Lancelot du Lac, The Death Song of Uther Pendragon).

Interestingly, spirits who reside outside the Spirit World, or who are summoned from it for a brief time, appear to retain their personality upon exiting it while spirits who escape or are released from the Spirit World become shadows of their former selves. For example, Ygraine appeared to retain her personality and love for her son when she was briefly summoned from the Spirit World (The Sins of the Father), while her husband Uther, who was accidentally released into the living world, became single-mindedly obsessed with Camelot (The Death Song of Uther Pendragon).

Abilities

The Shrine Boy possesses Elyan.

Spirits appear to possess a number of abilities. They can interact with both people and objects; appear and disappear at will; pass through solid objects; and possess the living.

Sorcerers appear to retain their magical abilities after death. The Seer Taliesin, for example, who may have appeared to Merlin as a spirit, was able to use his magic to heal Arthur of an arrow wound (The Crystal Cave).

Interestingly, the spirits of non-magical people have been able to use magic when outside of the Spirit World. Uther, for example, was able to use magic to levitate objects and start a fire after he was accidentally released (The Death Song of Uther Pendragon). Ygraine, however, who was merely summoned from the Spirit World for a short time, did not appear to have gained any magical abilities (The Sins of the Father).

Both magical and non-magical people appear to gain knowledge after their death. For example, Freya was aware that Morgause had used the Cup of Life to create an army of the undead, that the magical sword Excalibur could kill the undead, and that Merlin had hidden the sword in the Lake of Avalon (The Coming of Arthur); and Uther was aware that Arthur had married Guinevere, which occurred after his death (The Death Song of Uther Pendragon).