The Fomorroh will suck the life force out of you, everything that makes you Merlin will be gone, and in its place there will be just one thought. One thought that will grow until it's consumed you completely. One thought that will be your life's work. You will not be able to rest until it's done.

The Fomorroh is a serpent-like creature of the Old Religion, used by High Priestesses to control a person's mind.

History of the Fomorroh. Edit

In the days of the Old Religion, the High Priestesses would use the Fomorroh to enslave the minds of their enemies. Morgana's comments about summoning it from the depths and it not being used to the light, imply that this creature dwells in the Spirit world. To call it into this world, Morgana casts a spell, ("Astige ðu wyrm fah ond geþéowe ðæt mod ðisse þeowes. Hine bind ond ða heold ond awendaþ he ealle") on a medallion, on which the Fomorroh was represented, and threw it in the fire.


The medallion that represents the Fomorroh. It also resembles the sacred Rowan Tree, perhaps alluding to a connection between the two.

In her plan to kill Arthur, Morgana summons a Fomorroh and uses one of its heads to enslave Merlin, forcing him to try to eliminate the King. After several of his attempts on Arthur's life fail, Gwen and Gaius manage to catch Merlin. Gaius removes the Fomorroh and kills it, but a second one grows in its place. After stopping yet another attempt to kill Arthur, Gaius paralyses the snake's head, which temporarily gives Merlin back his free will. Under the disguise of Emrys, he travels to Morgana's hovel, finds the mother beast, and kills it after prevailing in a close battle with Morgana.
Fomorroh book s04e06

Illustration and description of the creature in one of Gaius' books.

Back in Camelot, Gaius removes the head still left in his neck (A Servant of Two Masters).

Shortly before Morgana wakes up from her encounter with Emrys, she has flashes of him stealing the Fomorroh and defeating her in a duel, which results in a series of events to discover his identity (The Secret Sharer).

Appearance Edit


The Fomorroh in Merlin's neck

The Fomorroh resembles a snake with a wide, short body and seven heads. Its necks are long for the body's length, which is about half a foot. Fomorroh has greyish skin and yellow eyes. When infecting someone, it is still visible by its grey colour and shape. You can paralyse it for a concise period of time before it wakes up.

Abilities Edit

As a creature of dark magic, the Fomorroh is a very dangerous being. Once placed inside somebody, it causes whatever instruction the person is given to become the only thing that they can think about and forces them to perpetrate whatever action they have been told to do. According to Morgana, the Fomorroh could suck the life force out of its victim and remove their current personality when corrupting a victim completely.


Morgana summons the Fomorroh.

Victims of the Fomorroh retain their memories, but their personality changes, causing them to become rude and hostile to others, and obsessed about performing the mission. An affected person can temporarily regain control if the head, that has been placed under the neck's skin, is paralysed, but only for around 24 hours.


Morgana implanting the Fomorroh into Merlin's neck

The creature is difficult to kill; even if one of its heads was cut off, another one would quickly grow in its place, and the disembodied head would stay alive. After Gaius had removed the serpent, it still grew back in Merlin's neck. The only way to definitively kill this creature is to kill the mother beast, by burning it in a fire and enchanting it with the following incantation: "'Ontende þisne wyrm þæt he licgeþ unastyred 'a butan ende."

Appearances Edit

Series 4
A Servant of Two Masters
The Secret Sharer (Appears in flashbacks) (cameo)

Trivia Edit

  • Body-wise the creature resembles a hydra, from Greek mythology, both in the number of heads and the idea of them growing back if decapitated. Unlike the hydra, it only grows one new head, instead of two.
  • The creature's name may have been inspired by the Fomorians, sometimes referred to as Fomorii, or simply Fomor. The Fomorians are a race of supernatural creatures from Irish folklore said to have inhabited the land prior to the Tuatha Dé Danann.
  • The creature's control over the subject appears to limit some of their own creativity; when Merlin attempted to kill Arthur, he only attempted to do so with conventional methods, such as rigging a crossbow or tainting Arthur's bath, without any sign that he even considered using his magic, suggesting that Morgana 'instructed' the fomorroh to make Merlin kill Arthur using only what she believed he was capable of, rather than allowing him free reign in a manner that might have 'inspired' him to use magic.
Series 4 Enemies
The Darkest Hour: MorganaMorgauseThe DorochaThe CailleachAgravaineWilddeorenWyvern
The Wicked Day: King OdinMorganaAgravaineThe GleemanGeldred
Aithusa: Julius BordenKing Odin
His Father's Son: MorganaAgravaineQueen AnnisKing CaerleonDerian
A Servant of Two Masters: MorganaAgravaineFomorrohMerlin (indirect)
The Secret Sharer: MorganaAgravaineAlatorOrn
Lamia: LamiaAgravaine
Lancelot du Lac: MorganaLancelot (Shade) •  AgravaineDochraid
A Herald of the New Age: Shrine BoyElyan (indirect)
The Hunter's Heart: MorganaAgravaineHelios
The Sword in the Stone: MorganaAgravaineHeliosAithusaNathair
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