Possession is a form of powerful magic that allows a spirit or creature to enter and take control of a person's body.
History[]

Cornelius Sigan gained immortality by sealing his soul in an enchanted jewel. When Cedric tried to steal the jewel, Sigan's spirit possessed him and used his body to take revenge on Camelot.
Sigan later killed and abandoned Cedric's body when he decided to take over Merlin instead. However, Merlin used a spell given to him by Kilgharrah to trap his spirit back inside the jewel (The Curse of Cornelius Sigan).
Gaius was possessed by a Goblin that Merlin accidentally released from the castle library. It entered his body by transforming itself into a small sphere of light and flying into his ear, and was later forced to leave when Merlin poisoned him (Goblin's Gold).
Princess Elena of Gawant was possessed by a Sidhe as an infant as part of a plot to gain control over the throne of Camelot. Forunately, Merlin and Gaius forced the Sidhe out of her with a potion developed by the Witches of Meredor (The Changeling).
Gaius's former fiancée Alice was possessed by a Manticore. Under its influence, she was forced to poison Uther and was unable to reveal any information the Manticore didn't want her to (Love in the Time of Dragons).
After Merlin was captured by her men, Morgana used a Fomorroh to take possession of his mind. She inserted the Fomorroh into his neck, then instructed him to kill Arthur. Merlin later freed himself from the Fomorroh's control by burning it (A Servant of Two Masters).

The Shrine Boy's spirit leaves Elyan.
When Elyan accidentally disturbed a Druid Shrine, he became possessed by the spirit of a young Druid boy. The boy wanted to find peace in the spirit world by avenging his death, which had been caused by Arthur.
Eventually, the boy took complete control over Elyan's body to the point where he spoke with the boy's voice instead of his own. The boy later released Elyan when Arthur proved his remorse by promising that the Druids would be treated with respect from then on, allowing the boy to find peace (A Herald of the New Age).
Appearances[]
- Series 2
- The Curse of Cornelius Sigan
- Series 3
- Goblin's Gold
- The Changeling
- Series 4
- A Servant of Two Masters
- A Herald of the New Age