Merlin (Welsh: Myrddin, Cornish: Merdhyn, Breton: Merzhin)[note 2] is a mythical figure prominently featured in the legend of King Arthur and best known as a magician, with several other main roles.

[note 3] The familiar depiction of Merlin, based on an amalgamation of historical and legendary figures, was introduced by the 12th-century Catholic cleric Geoffrey of Monmouth and then built on by the French poet Robert de Boron and prose successors in the 13th century.

[6] Later chronicle and romance writers in France and elsewhere expanded the account to produce a more full, multifaceted character, creating one of the most important figures in the imagination and literature of the Middle Ages.

A popular version from the French prose cycles tells of Merlin being bewitched and forever sealed up or killed by his student, the Lady of the Lake, after having fallen in love with her.

Medievalist Gaston Paris suggests that Geoffrey chose the form Merlinus rather than the expected *Merdinus to avoid a resemblance to the Anglo-Norman word merde (from Latin merda) for feces.

Folklorist Jean Markale proposed that the name of Merlin is of French origin and means 'little blackbird', an allusion to the mocking and provocative personality usually attributed to him in medieval stories.

[10]: 58 In Welsh poetry, Myrddin was a bard who was driven mad after witnessing the horrors of war and subsequently fled civilization to become a wild man of the wood in the 6th century.

While Nennius' "fatherless" Ambrosius eventually reveals himself to be the son of a Roman consul, Geoffrey's Merlin is fathered by an incubus demon through a nun, daughter of the King of Dyfed (Demetae, today's South West Wales).

[note 4] In the second, Merlin's magic enables the new British king, Uther Pendragon, to enter into Tintagel Castle in disguise and to father Arthur with his enemy's wife, Igerna (Igraine).

Merlin spends a part of his life as a madman in the woods and marries a woman named Guendoloena (a character inspired by the historic king Gwenddoleu ap Ceidio).

[39] According to Villemarqué, the origin of the legend of Merlin lies with the Roman story of Marsus, a son of Circe, which eventually influenced the Breton and Welsh tales of a supernaturally-born bard or enchanter named Marzin or Marddin.

[52] In this text, also known as the Suite du Merlin, the mage both predicts and, wielding elemental magic,[25] influences the course of battles,[note 9] in addition to helping the young Arthur in other ways.

[61] Conversely, Merlin seems to be inherently evil in the so-called non-cyclic Lancelot, where he was born as the "fatherless child" from not a supernatural rape of a virgin but a consensual union between a lustful demon and an unmarried beautiful young lady and was never baptized.

[62][63] As the Arthurian myths were retold, Merlin's prophetic "seer" aspects were sometimes de-emphasized (or even seemingly vanish entirely, as in the fragmentary and more fantastical Livre d'Artus[25]) in favor of portraying him as a wizard and an advisor to the young Arthur, sometimes in the struggle between good and evil sides of his character, and living in deep forests connected with nature.

[68] An even more political Italian text was Joachim of Fiore's Expositio Sybillae et Merlini, directed against Frederick II, Holy Roman Emperor whom the author regarded as the Antichrist.

The Orygynale Cronykil of Scotland, which sympathizes with Mordred as usual in Scottish chronicle tradition, particularly attributes Merlin's supernatural evil influence on Arthur to its very negative portrayal of his rule.

Bauduin (Baudouin) Butor's 1294 romance known as either Les Fils du Roi Constant or Pandragus et Libanor names Merlin's usually unspecified mother as Optima, daughter of King Melias of Demetia (Dyfed), while Paolino Pieri's 14th-century Italian La Storia di Merlino calls her Marinaia.

In English-language medieval texts that conflate Britain with the Kingdom of England, the Anglo-Saxon enemies against whom Merlin aids first Uther and then Arthur tend to be replaced by the Saracens[73] or simply just invading pagans.

[25] During the 15th century, Welsh works predicting the Celtic revenge and victory over the Saxons were recast as Merlin's (Myrddin's) prophecies and used along with Geoffrey by the propaganda of the Welsh-descended Henry VII of England (who fought under the red dragon banner) of the House of Tudor, which traced its lineage directly to Arthur.

Later, the Tudors' Welsh supporters, including bards, interpreted the prophecy of King Arthur's return as having been fulfilled after their ascent to the throne of England that they sought to legitimize following the Wars of the Roses.

[note 12] In the Prophéties de Merlin, he also tutors Sebile, two other witch queens, and the Lady of the Isle of Avalon (Dama di Isola do Vallone).

In the prose chivalric romance tradition, Merlin has a major weakness that leads him to his relatively early doom: young beautiful women of femme fatale archetype.

Usually (including in Le Morte d'Arthur), having learned everything she could from him, Viviane will then also replace the eliminated Merlin within the story, taking up his role as Arthur's adviser and court mage.

The exact form of his prison or grave can be also variably a cave, a tree, or hole either within or under a large rock (according to Le Morte d'Arthur, this happens somewhere in Benwick, the kingdom of Lancelot's father[85]), or an invisible tower made of magic with no physical walls.

[87] A Breton tradition cited by Roger Sherman Loomis in Celtic Myth and Arthurian Romance (where he also asserts that it "seems almost certain that Morgan le Fay and the Lady of the Lake were originally the same person" in the legend) has Merlin trapped by his mistress inside a tree on the Île de Sein.

[89] One notably alternate version that has a happier ending for Merlin is the Premiers Faits section of the Livre du Graal, where Niniane peacefully confines him in Brocéliande with walls of air, visible only as a mist to others but as a beautiful yet unbreakable crystal tower to him (only Merlin's disembodied voice can escape his prison one last time when he speaks to Gawain[89] on the knight's quest to find him), where they then spend almost every night together as lovers.

"[96] According to Stephen Thomas Knight, Merlin embodies a conflict between knowledge and power: beginning as a symbol of wisdom in the first Welsh stories, he became an advisor to kings in the Middle Ages, and eventually a mentor and teacher to Arthur and others in the works around the world since the 19th century.

[97] Since the Romantic period, Merlin has been typically depicted as a wise old man with a long white beard, creating a modern wizard archetype reflected in many fantasy characters,[98] such as J. R. R. Tolkien's Gandalf[25] or J. K. Rowling's Dumbledore,[99] who also use some of his other traits.

The ability of this complex figure to endure for more than fourteen centuries results not only from his manifold roles and their imaginative appeal, but also from significant, often irresolvable tensions or polarities [...] between beast and human (Wild Man), natural and supernatural (Wonder Child), physical and metaphysical (Poet), secular and sacred (Prophet), active and passive (Counselor), magic and science (Wizard), and male and female (Lover).

Interwoven with these primary tensions are additional polarities that apply to all of Merlin's roles, such as those between madness and sanity, pagan and Christian, demonic and heavenly, mortality and immortality, and impotency and potency.