Welsh mythology, also called Y Chwedlau (which means "the legends" in Welsh), includes traditions from Wales and those created by the Celtic Britons in other areas before the end of the first millennium. In societies that relied mostly on spoken stories, Celtic myths and history were recorded by experts like druids (called derwyddon in Welsh). Over time, these stories were lost or changed because of outside influences and invasions. Many of these altered stories and history are found in medieval Welsh manuscripts, such as the Red Book of Hergest, the White Book of Rhydderch, the Book of Aneirin, and the Book of Taliesin. Other works connected to Welsh mythology include the ninth-century Latin historical text Historia Brittonum ("History of the Britons") and Geoffrey of Monmouth's 12th-century Latin chronicle Historia Regum Britanniae ("History of the Kings of Britain"). Later Welsh folklore, like the stories collected in The Welsh Fairy Book by William Jenkyn Thomas (1908), is also linked to Welsh mythology.

Cosmogony and creation

The Insular Celts, like other Celtic groups, did not leave behind direct written records about the origins of the universe. However, it is likely that they had detailed creation stories, as ancient writers described the druids—spiritual leaders who passed down knowledge through spoken traditions—as highly knowledgeable.

Scholars find links between Celtic beliefs and the broader Proto-Indo-European mythological system. These connections appear in the names of gods and in later written stories, which may preserve older oral tales. However, these stories were not written until after Christianity spread in Britain, making the information indirect. Over time, these stories likely changed, as myths often do.

John T. Koch suggests that the name of the goddess Dôn may come from an ancient word meaning "the earth." In this way, she represents the Welsh version of a Proto-Indo-European Earth Goddess, from whom all other gods are believed to have originated. According to this idea, the "Children of Dôn" could be similar to the Greek Titans.

John Carey notes that the Fourth Branch of The Mabinogi and certain poems, like Cad Goddeu, contain clues about the repeating nature of creation stories.

Claude Sterckx proposes that Celtic myths suggest a cyclical view of creation. A common story pattern involves a hero or king and a goddess of the earth or sovereignty facing a rival for the goddess’s affection before uniting to have a son who symbolizes life. These figures eventually die, allowing the cycle to begin again. For example, John Koch suggests that the Welsh figures Gwron ("divine husband") and Modron ("divine mother") created Mabon ("divine son"). This pattern also appears in The Mabinogion, where Pwyll and Rhiannon unite after facing Gwawl to have a son, Pryderi. In both stories, the divine son is taken shortly after birth, and the parents must wait years before reuniting with him.

These patterns suggest that the transformations of characters, such as Lleu and Taliesin, may represent not only reincarnation but also changes in the cosmos itself, similar to the Norse idea of Ragnarok, which marks the end of one world and the beginning of another.

1) Elfydd: The Earth; the realm of humans.
2) Annwn: The Otherworld; the realm(s) of the gods. Some sources describe it as an underworld beneath the earth, where souls wait to be reborn. Others see it as hidden parts of the natural world, such as deep forests or near lakes. The Celts likely viewed the Otherworld as part of nature, not separate from it, and as a parallel to Elfydd.

While the sky and its stars are clearly separate from the earth, there is little evidence in Welsh myths that gods are associated with the sky. However, earlier beliefs may have linked the sky to the divine, as suggested by a phrase in The Book of Taliesin: "in the Un-world below Elfydd, in the air above Elfydd."

Sharon Paice Macleod suggests that the ancient Celts may have believed in a "World Tree" that connected different realms, similar to the Norse Yggdrasil. This idea is supported by the importance of trees in Celtic traditions. However, there is no clear proof of this belief.

Legends

The stories in the Mabinogion are found in real literary works, not just in theories or myths made by scholars. The Mabinogion includes four stories called the Four Branches of the Mabinogi. These stories focus on the actions of British gods who were later changed into kings and heroes in Christian stories. The only character who appears in all four stories is Pryderi fab Pwyll, the king of Dyfed. He is born in the first story, dies in the fourth, and is likely based on the Celtic god Maponos. The only other characters who appear in more than one story are Pryderi’s mother, Rhiannon, and the British prince Manawydan, who later becomes Rhiannon’s second husband. Manawydan and his siblings, Brân the Blessed, Branwen, and Efnysien, are central to the second story. The fourth story focuses on the family of Dôn, including the wizard Gwydion, his nephew Lleu Llaw Gyffes, and his sister Arianrhod.

The first story describes how Pwyll, the prince of Dyfed, swaps places with Arawn, the ruler of Annwn (the otherworld), for a year. Pwyll defeats Arawn’s enemy, Hafgan, and returns to find Rhiannon, a beautiful woman whose horse is impossible to catch. Pwyll wins Rhiannon’s hand in marriage by outsmarting Gwawl, who was originally promised to her. Rhiannon gives birth to a son, but the child disappears soon after. Rhiannon is blamed for the child’s disappearance and forced to carry guests on her back as punishment. The child is taken by a monster but is later rescued by Teyrnon and his wife, who raise him as their own, naming him Gwri of the Golden Hair. When the boy looks like Pwyll, he is returned to his real parents. The boy is renamed Pryderi, and Rhiannon is freed from her punishment.

In the second story, Branwen, the sister of Brân the Blessed, is married to Matholwch, the king of Ireland. Branwen’s half-brother, Efnysien, insults Matholwch by damaging his horses. Brân gives Matholwch new horses and a magical cauldron that can bring the dead back to life as compensation. Matholwch and Branwen have a son named Gwern, but Matholwch mistreats Branwen. Branwen sends a starling to warn Brân, who then goes to war against Matholwch. Brân’s army crosses the Irish Sea, but Brân is so large that he walks across. The Irish offer peace and build a house for Brân, but inside, they hide armed warriors in bags they claim contain flour. Efnysien kills the warriors by squeezing the bags. Later, Efnysien throws Gwern into a fire, causing a battle. Efnysien destroys the magical cauldron to stop the Irish from reviving their dead, but he dies in the process. Only seven Britons survive, including Pryderi, Manawydan, and the mortally wounded Brân. Brân asks his companions to cut off his head and take it back to Britain. Branwen dies of grief, and five pregnant women survive to repopulate Ireland.

Pryderi and Manawydan return to Dyfed, where Pryderi marries Cigfa and Manawydan marries Rhiannon. A mist covers the land, making it empty and desolate. They survive by hunting, then move to England, where they make saddles, shields, and shoes of such high quality that local craftsmen are driven away. They return to Dyfed and become hunters again. A white boar leads them to a mysterious castle. Pryderi enters the castle against Manawydan’s advice and does not return. Rhiannon investigates and finds Pryderi clinging to a bowl, unable to speak. The same fate befalls Rhiannon, and the castle disappears. Manawydan and Cigfa return to England as shoemakers but are again driven away. They return to Dyfed and sow three fields of wheat. The first two fields are destroyed, and the third is ruined by mice. Manawydan captures the mouse’s leader and refuses to spare it, demanding the release of Pryderi and Rhiannon and the end of the enchantment over Dyfed. A bishop agrees, revealing the mouse is his wife, who has been waging magical war against Dyfed because she is friends with Gwawl, whom Pwyll, Pryderi’s father, humiliated.

While Pryderi rules Dyfed, Math, son of Mathonwy, rules Gwynedd in northern Wales. Math’s feet must be held by a virgin unless he is at war. Math’s nephew, Gilfaethwy, loves Goewin, his current footholder. Gilfaethwy’s brother, Gwydion, tricks Math into going to war against Pryderi so Gilfaethwy can be with Goewin. Gwydion kills Pryderi in battle, and Gilfaethwy rapes Goewin. Math marries Goewin to save her from disgrace and banishes Gwydion and Gilfaethwy, transforming them into deer, pigs, and wolves. After three years, they return as humans.

Math needs a new footholder and chooses Gwydion’s sister, Arianrhod. When Math tests Arianrhod’s virginity, she gives birth to two sons. One, Dylan, joins the sea, while the other is raised by Gwydion. Arianrhod refuses to name or arm Gwydion’s son unless she does it. Gwydion tricks her into naming him Lleu Llaw Gyffes and giving him arms. Arianrhod then tells Gwydion that Lleu will never have a wife from Earth, so Gwydion and Math create a wife from flowers, named Blodeuwedd. Blodeuwedd falls in love with a hunter, Gronw Pebr, and they plot to kill Lleu. Blodeuwedd tricks Lleu into revealing how he can be killed, but when Gronw tries, Lleu escapes by turning into an eagle. Gwydion restores Lleu to human form and turns Blodeuwedd into an owl. Gronw offers to compensate Lleu, but Lleu insists on returning the blow. Lleu kills Gronw with a spear thrown so hard it pierces him through the rock he hides behind.

A large tradition once surrounded the Battle of the Trees, a mythological war between the sons of Dôn and the forces of Annwn, the Welsh Otherworld, connected to the Fourth Branch of the Mabinogi. Amaethon, a son of Dôn, steals a white roebuck and a whelp from Arawn, king of Annwn, causing a great battle. Gwydion fights alongside his brother and, with Lleu’s help, enchants trees and sedges to rise as warriors against Arawn’s forces. The alder leads the attack, the aspen falls in battle, and the oak trembles heaven and earth. The bluebells cause confusion, but the holly, green-tinted, is the hero. A warrior fighting for Arawn cannot be defeated unless his enemies guess his name. Gwydion guesses the warrior’s name by recognizing alder sprigs on his shield and sings two englyns (a type of poem) to defeat him.

This account is very different from Geoffrey of Monmouth’s description of Maximian (as he calls him) in *Histor

Characters

The Welsh people had been Christian for many years before their old myths were written down. Over time, their gods became heroes and kings from the past. Many characters who show powers or divine traits are part of two groups: the Plant Dôn ("Children of Dôn") and the Plant Llŷr ("Children of Llŷr").

Dôn, the daughter of Mathonwy, was the leader of one family. Her husband’s name is not given.

• Gwydion: A powerful magician and warrior. He appears mainly in the fourth branch of the Mabinogi, as well as in the Welsh Triads, the Englynion y Beddau, and several poems in the Book of Taliesin.
• Arianrhod: Gwydion’s main opponent; she is the mother of Lleu. According to one of the Welsh Triads, her father was Beli Mawr (see Family of Beli Mawr).
• Eufydd fab Dôn: A character with little known about him; likely connected to the Gaulish god Ogmios. He appears in two poems from the Book of Taliesin.
• Gilfaethwy: Appears in Math fab Mathonwy, as well as in several French Arthurian tales under the name Griflet filz Do.
• Gofannon: A metalsmith believed to be related to the Irish Goibniu and the Gallo-Roman god Gobannus. He is mentioned in both Culhwch and Olwen and Math fab Mathonwy; in the latter, he is blamed for the death of his nephew, Dylan.
• Amaethon: A god of farming, mentioned in Culhwch and Olwen and more clearly in Cad Goddeu, where he causes a war between Gwynedd and Annwn.

Other figures linked to the Children of Dôn include:

• Math fab Mathonwy: Dôn’s brother, a skilled wizard and king of Gwynedd. He appears in the fourth branch of the Mabinogi, as well as in the Welsh Triads and medieval Welsh poetry.
• Dylan ail Don: The first son of Arianrhod, who "became like the sea" and "swam as well as the best fish." He was killed by his uncle Gofannon. He appears in Math fab Mathonwy and the Death Song of Dylan in the Book of Taliesin.
• Lleu: Arianrhod’s second son and Dylan’s twin brother. He appears in the fourth branch of the Mabinogi, which describes his birth, marriage, death, resurrection, and becoming king of Gwynedd. He is also mentioned in the Welsh Triads and medieval poems. He is related to the Gaulish god Lugus and similar to the Irish god Lugh Lámhfhada.
• Blodeuwedd: A woman made by Math and Gwydion from flowers to be Lleu’s wife. She betrayed him for her lover, Gronw. Gwydion changed her into an owl for her crimes. She appears in Math fab Mathonwy.
• Gronw "the Radiant": The lord of Penllyn who conspired with Blodeuwedd to kill Lleu. He appears in Math fab Mathonwy.

Llŷr, the leader of the other family, may have been inspired by the Irish sea god Ler. His nickname, Llediaith ("half-speech"), suggests a foreign origin. His wife was Penarddun. According to the Mabinogion, she was the mother of Llŷr’s three children and two others by Euroswydd. The Mabinogi names her as a daughter of Beli Mawr, though this might be a mistake for "sister." Penarddun and Llŷr’s children include:

• Brân the Blessed: Appears mainly in Branwen ferch Llyr, where he is a giant and king of Britain. He invades Ireland to help his sister, who was mistreated by the Irish king Matholwch. He is killed by a poisoned spear and buried in London. His head protected Britain from invaders until King Arthur later uncovered it. He also appears in medieval Welsh poetry, the Welsh Triads, and Cad Goddeu. Some scholars compare him to the Gaulish leader Brennus. His son, Caradog, was left to defend Britain but was killed by his uncle Caswallawn.
• Manawydan: Bran’s younger brother, who fought alongside him in Ireland. He is one of only seven men to survive the final battle and later lives in Dyfed with Pryderi. He refuses to claim the British throne, which was taken by his cousin Caswallawn. He marries Rhiannon in the Third Branch and saves Dyfed from a wizard’s curse. He is often linked to the Irish sea god Manannán mac Lir.
• Branwen: The family’s only daughter. Her mistreatment by her husband, Matholwch, caused a war between Britain and Ireland, leading to the deaths of her brothers, her son, and her husband. She dies of grief after seeing the battle. Her infant son, Gwern, was murdered by her uncle Efnysien.

Other figures linked to the Children of Llŷr include:

• Euroswydd: The father of two children with Penarddun.
• Efnysien and Nisien: Euroswydd’s sons. Efnysien is cruel and caused the war with Ireland, while Nisien is kind. Both died in the final battle, with Efnysien sacrificing himself to destroy the "Cauldron of Rebirth."
• Matholwch: King of Ireland, who

King Arthur

Arthurian stories became popular across Europe, but the Welsh people can claim to have the earliest mentions of Arthur. Before Arthur became famous worldwide, stories about him were mostly found in the Brythonic regions of Wales, Cornwall, and Brittany. These stories are divided into two groups: those from before Geoffrey of Monmouth’s work and those from his writings. Wales also played a role in shaping the Arthur of the Romance Tradition after Arthur became a widely known figure.

• Y Gododdin includes a short line: "he was no Arthur."
• Taliesin’s poems, such as Kadeir Teyrnon ("The Chair of the Prince"), which calls Arthur "the Blessed," Preiddeu Annwn ("The Spoils of the Annwn"), which describes Arthur’s journey to the Otherworld, and Marwnat Uthyr pen[dragon] ("The Elegy of Uthyr Pen[dragon]"), which mentions Arthur’s bravery and suggests a father-son relationship between Arthur and Uthyr that existed before Geoffrey of Monmouth’s writings.
• The Black Book of Carmarthen includes Pa gur yv y porthaur? ("What man is the gatekeeper?"), a dialogue between Arthur and a fortress gatekeeper, where Arthur lists his name and the deeds of his men, including Cei and Bedwyr.
• The Welsh tale Culhwch and Olwen (about 1100), which is part of the modern Mabinogion collection.
• Arthur is mentioned many times in the Welsh Triads, a collection of short summaries about Welsh traditions. In these stories, Arthur’s court represents all of legendary Britain, and "Arthur’s Court" is sometimes used instead of "The Island of Britain" in phrases like "Three XXX of the Island of Britain."
• Historia Britonum: Chapter 56 describes twelve battles won by Arthur, who is called dux bellorum (war leader) rather than king.
• Annales Cambriae includes entries about Arthur, Medrod, and Merlin (Myrddin):
• Year 72 (about 516): The Battle of Badon, where Arthur carried the cross of Jesus Christ for three days and three nights, and the Britons won.
• Year 93 (about 537): The Strife of Camlann, where Arthur and Medraut died, and there was death in Britain and Ireland.
• Year 129 (about 573): The Battle of Arfderydd, where Guendoleu fell and Merlin went mad.
• Several saints’ lives: Arthur appears in writings about post-Roman saints, such as the Life of Saint Gildas, Life of Saint Cadoc, and others. A less legendary account of Arthur is found in Legenda Sancti Goeznovii, which may date to the early 11th century.
• De Gestis Regum Anglorum and De miraculis sanctae Mariae Laudunensis by William of Malmesbury and Herman provide the first clear evidence that Arthur was believed to be alive and would return someday.

• Prophetiae Merlini: Geoffrey of Monmouth presented apocalyptic stories as the work of Merlin, who was previously known as "Myrddin." These prophecies were widely read and believed, similar to Nostradamus’s prophecies centuries later.
• Historia Regum Britanniae: After the Romans left, Vortigern took power and invited the Saxons to fight for him. The Saxons later rebelled, and Britain remained in war under Aurelius Ambrosius and his brother Uther Pendragon, helped by Merlin. Arthur defeated the Saxons, conquered much of northern Europe, and brought peace until the Roman emperor Lucius Tiberius demanded tribute from Britain. Arthur defeated Lucius in Gaul but was mortally wounded when his nephew Modred seized the throne. Arthur returned, killed Modred, and was taken to the isle of Avalon, leaving the kingdom to his cousin Constantine. After Arthur’s death, the Saxons returned and grew stronger.
• Vita Merlini: This work includes Geoffrey’s retelling of the Welsh legend of Myrddin, along with other sources and elements from saints’ lives and natural history. Written in Latin verse (hexameter), it is Geoffrey’s only known poem.

Each of these stories is part of the modern Mabinogion collection and may be based on the romances of Chrétien de Troyes, though they could also share a common Celtic source. For more details on these tales, see the section on "The Three Romances" in The Mabinogion.

• Owain, or The Lady of the Fountain
• Peredur Son of Efrawg
• Gereint Son of Erbin

Folklore

Welsh folklore includes many mythical creatures and beings. These include:
– Adar Llwch Gwin: Giant birds that understand human languages.
– Afanc: A lake monster (the exact lake varies by story).
– Bendith y Mamau: Another name for the Tylwyth Teg or Welsh fairy folk, meaning "Blessings of the Mothers" (Mother Goddesses).
– Brenin Llwyd: A silent, ghostly, and partly visible figure found in mountainous areas of Wales. It is described as cloaked in mist and preys on travelers and children.
– Bwbach (plural Bwbachod): A household spirit similar to a brownie or hobgoblin. It is hardworking but mischievous. It expects only a bowl of cream each night for its services. However, it dislikes clergymen and teetotalers, whom it will tease relentlessly.
– Bwca: A brownie that performs housework in exchange for bread and milk. If disrespected, it may become angry and leave. Trickery, such as learning its name, also causes it to leave. In one tale, a bwca became upset after its human friend was killed in war and played disruptive pranks until a magician banished it.
– Ceffyl Dŵr: A water horse similar to the Kelpie.
– Cewri (Giants): Such as Ysbaddaden Bencawr from Culhwch and Olwen and Brân from The Four Branches of the Mabinogi.
– Coblynau: Small people and mine spirits, like the Knocker.
– Coraniaid: A mysterious race of beings that troubled the Island of Britain.
– Cŵn Annwn: Hunting dogs of the Otherworld.
– Cyhyraeth: A death spirit.
– Y Diawl (The Devil): Said to have built bridges in Wales, including Devil’s Bridge in Ceredigion. It appears to sinners as a horned, black-faced shepherd with a pack of dogs. It is sometimes linked to Yr Hwch Ddu Gwta, a bobtailed black sow.
– Dreigiau (Dragons): The most famous is Y Ddraig Goch (the Red Dragon).
– Y Dyn Hysbys (The Wise Man): A wizard, cleric, or someone who learns about medicine, magic, or family-inherited powers. They can predict the future on Ysbrydnos (spirit night) and create charms to protect against evil.
– Gwiddonod (Witches): Old women who cast spells, ride broomsticks, tell fortunes, and use charms to heal or cause illness. They can transform into hares and can only be killed by a silver bullet. Only Y Dyn Hysbys can undo their harm.
– Gwragedd Annwn: Beautiful lake maidens.
– Gwyllgi: A large black dog that haunts lonely roads.
– Gwyllion: Mountain spirits that look like hags.
– Llamhigyn y Dŵr: A winged toad-like lake creature, also called a water leaper.
– Mallt-y-Nos: Female spirits of Annwn, linked to the Wild Hunt.
– Morgens: Water spirits.
– Plentyn Newid: The Welsh version of the Changeling creature.
– Pwca: A shapeshifting animal spirit.
– Tylwyth Teg: Literally "the Fair Folk," the common name for Welsh fairy folk who live in the Otherworld.
– Ysbrydion (Spirits): More likely to appear to humans on Ysbrydnos (spirit night), such as Calan Gaeaf or Calan Mai.

Welsh folklore includes folk tales, legends, traditions, and anecdotes. The cyfarwyddiaid (singular: cyfarwydd, "storyteller") were members of the bardic order in Wales. The only named historical cyfarwydd is Bledri ap Cydifor.

The cyfarwyddiaid were a learned class with duties and education beyond those of a common poet. They were court officials with training in their art and had close relationships with their lords. Their duties included praising, celebrating, and mourning their lords. Welsh folklore includes tales preserved and told by the cyfarwyddiaid, who also protected the genealogies of powerful families.

Stories were shared as proverbs, songs, and spoken tales. Historical and non-historical tales were often told together without clear distinction. This helped teach culture and history through the poetry of the time. In earlier periods, the penceirddiaid told stories in the courts of princes and nobles. Later, the cyfarwyddiaid told stories to audiences beyond nobility.

Medieval folklore followed rules and themes, such as poetic triads, old verse, and historical knowledge. Stories often had a chronological structure with short episodes, reflecting their oral origins. Welsh folklore was compared to Irish literature, which shared similar structures and aimed to inform about the past rather than criticize ancestry. Both used prose with poetry, and both relied on classes of gentry to preserve tales. However, in Ireland, bards were not storytellers; that role belonged to poets.

Storytelling in Wales and Ireland was believed to come from spiritual inspiration. Poets spoke with great knowledge, sometimes gained through divination (called áí in Irish and awen in Welsh). Welsh cyfarwyddiaid were called awenyddion, believed to deliver prophetic speech during moments of awen. Other customs also arose from Welsh folklore.

Folk tales and legends survived through retellings by common people. Storytelling occurred in many forms, such as gossip, games, dancing, riddles, nursery rhymes, and songs. Common times for storytelling included "merry evenings" (nosweithiau llawen), "knitting nights" (nosweithiau gwau), and Calan Gaeaf (Winter’s Eve).

Famous tales include those about the "Oldest Animals," where a character gathers information from animals until the oldest is found. These include the Blackbird of Cilgwri, the Stag of Rhedynfre, the Owl of Cwm Cowlyd, the Eagle of Gwernabwy, and the Salmon of Llyn Llyw. The Triad "The Three Eld

Travelogue

Gerald of Wales wrote about many details of Welsh myths and stories in his books Itinerarium Cambriae (1191) and Descriptio Cambriae (1194).

National histories

The following works are seen as historical writings, but they describe a story that later became a widely believed origin tale for the Welsh.

• Historia Britonum
• Annales Cambriae
• The works of Geoffrey of Monmouth

Legacy of Welsh mythology in English literature

• Arthurian tales: See King Arthur
• The Mabinogion: See Mabinogion; William Morris published a work titled Love is Enough in 1872. This work is a poetic drama based on a story from The Mabinogion and includes woodcut illustrations by Burne-Jones. John Cowper Powys used myths from The Mabinogion in his Welsh novels Owen Glendower (1941) and Porius (1951).
• Taliesin: Thomas Love Peacock wrote The Misfortunes of Elphin in 1829, which is about a character from the Taliesin tales. John Cowper Powys included characters such as Blodeuwedd, Myrddin Wyllt, and King Arthur in his novel Porius: A Romance of the Dark Ages (1951).
• Madoc: See Madoc