Rhiannon is a classic figure in Celtic or Welsh Literature, Welsh mythology or British mythology. She appears prominently in the Mabinogi. This is the chief prose literature of mediaeval Wales, compiled c.1100 from earlier oral traditions. It is culturally prominent in Welsh circles today, as well as popular in worldwide English translations. (The Mabinogi has also been known as the Mabinogion based on an old historical mistake.)
Rhiannon is therefore a major part of the earliest British prose texts to survive today, in two mediaeval manuscripts,  but retold today in countless publications as well as plays, film, storytelling and other arts.
Rhiannon's original story is mainly in the First Branch of the Mabinogi, with more following in the Third Branch. She is a strongminded Otherworld lady, who chooses Pwyll, prince of Dyfed as her consort, in preference to another man she had already betrothed. Their son is the hero Pryderi, who inherits the lordship of Dyfed. Rhiannon as a widow marries Manawydan of the British royal family, and has further adventures.
Like some other figures of Welsh literary tradition, Rhiannon may be a reflex of an earlier Celtic deity. Her name appears to derive from the reconstructed earlier Brittonic form Rigantona, as both their names mean Divine Queen. In the First Branch Rhiannon is strongly associated with horses, and so is her son Pryderi. She is often considered to be related to the Gaulish horse goddess Epona.  The resemblance is both in her horse affinity, and her son's, including mare and foals; and also a particular way of sitting on a horse in a calm, static way, which is like many images of Epona.  Ronald Hutton disagrees, saying that a horse is the only thing they have in common. but then there is not much else known of Epona than horses and the horseriding class.
Y Mabinogi: First Branch
Rhiannon first appears at Gorsedd Arberth an ancestral mound near one of the chief courts of Dyfed. Pwyll, the prince of Dyfed, has accepted the challenge of the mound's magical tradition to show a marvel or deal out blows. Rhiannon appears to him and his court as the promised marvel. She is a beautiful woman arrayed in gold silk brocade, riding a shining white horse. Pwyll sends his best horsemen after her two days running, but she always remains ahead of them, though her horse never does more than amble. On the third day he finally follows her himself and does no better, until he finally appeals to her to stop for him.
Rhiannon characteristically rebukes him for not considering his horse before, then explains she has sought him out to marry him, in preference to her current betrothed, Gwawl ap Clud. Pwyll gladly agrees, but at their wedding feast at her father's court, an unknown man requests Pwyll grant a request; which he does without asking what it is. The man is Gwawl, and he requests Rhiannon.
Rhiannon rebukes Pwyll a second time for his stupid words, but provides the means and the plan to salvage the situation. She holds a second wedding feast for Gwawl, where she deploys Pwyll's men outside in the orchard. She instructs Pwyll to enter the hall dressed as a beggar and humbly request Gwawl fill a certain 'small bag' with food. But she has enchanted the 'small bag' so it cannot ever be filled by normal means. Gwawl is persuaded to step in it to control its magic, which means Pwyll can trap him in it. Pwyll's men rush in and surround the hall, then beat and kick Gwawl as the Badger-in-the-Bag game. To save his life Gwawl is forced to relinquish Rhiannon completely, and also his revenge. Rhiannon marries Pwyll, then journeys to Dyfed as its queen.
After a happy two years Pwyll comes under pressure from his nobles, to provide an heir. He refuses to set Rhiannon aside as barren, and in the third year their son is born. However, on the night of his birth, the newborn disappears while in the care of Rhiannon's six sleepy maids. Terrified of being put to death, the women kill a puppy and smear its blood on Rhiannon's sleeping face. In the morning they accuse her of infanticide and cannibalism. Rhiannon takes counsel with her own advisers, and offers to undergo a penance. Pwyll is again urged to set her aside, but refuses, and sets her penance instead. She must sit every day by the gate of the castle at the horse block, to tell her story to travelers. She must also offer to carry them on her back as a beast of burden, though few accept this. However as the end of the story shows, Pwyll maintains her state as his queen, as she still sits at his side in the hall at feasting time.
The newborn child is discovered by Teyrnon, the lord of Gwent-Is-Coed (SE Wales). He is a horse lord whose fine mare foals every May Eve, but the foals go missing each year. He takes the mare into his house and sits vigil with her. After her foal is born he sees a monstrous claw trying to take his the newborn foal through the window, so he slashes at the monster with his sword. Rushing outside he finds the monster gone, and a human baby left by the door. He and his wife claim the boy as their own naming him Gwri Wallt Euryn (English: Gwri of the Golden hair), for "all the hair on his head was as yellow as gold". The child grows at a superhuman pace with a great affinity for horses. Teyrnon who once served Pwyll as a courtier, recognises the boy's resemblance to his father. As an honorable man he returns the boy to the Dyfed royal house.
Reunited with Rhiannon the child is formally named in the traditional way via his mother's first direct words to him Pryderi a wordplay on "delivered" and "worry,”“care,” or "loss." In due course Pwyll dies, and Pryderi rules Dyfed, marrying Cigfa of Gloucester, and amalgamating the seven cantrefs of Morgannwg to his kingdom.
Y Mabinogi: Third Branch
Pryderi returns from the disastrous Irish wars as one of the only Seven Survivors. Manawydan is another Survivor, and his good comrade and friend. They perform their duty of burying the dead king of Britain's head in London (see Bendigeidfran) to protect Britain from invasion. But in their long time away the kingship of Britain has been usurped by Manawydan's nephew Caswallon.
Manawydan declines to make more war to reclaim his rights. Pryderi recompenses him generously by giving him the use of the land of Dyfed, though he retains the sovereignty. Pryderi also arranges a marriage between the widowed Rhiannon and Manawydan, who take to each other with affection and respect. Pryderi is careful to pay homage for Dyfed to the usurper Caswallon to avert his hostility.
Manawydan now becomes the lead character in the Third branch, and it is commonly named after him. With Rhiannon, Pryderi and Cigfa, he sits on the Gorsedd Arberth as Pwyll had once done. But this time disaster ensues. Thunder and magical mist descend on the land leaving it empty of all domesticated animals and all humans apart from the four protagonists.
After a period of living by hunting the four travel to borderland regions (now in England) and make a living at skilled crafts. In three different cities they build successful businesses making saddles, shields, then shoes. But vicious competition puts their lives at risk. Rather than fight as Pryderi wishes, Manawydan opts to quietly move on. Returning to Dyfed, Manaywdan and Pryderi go hunting and follow a magical white boar, to a newly built tower. Against Manawydan's advice, Pryderi enters it to fetch his hounds. He is trapped by a beautiful golden bowl. Manawydan returns to Rhiannon who rebukes him sharply for failing to even try to rescue his good friend. But her attempt to rescue her son suffers the same fate as he did. In a "blanket of mist", Rhiannon, Pryderi and the tower vanish.
Manawydan eventually redeems himself by achieving restitution for Rhiannon, Pryderi, and the land of Dyfed. This involves a quasi-comical set of magical negotiations about a pregnant mouse. The magician Llwyd ap Cilcoed is forced to release both land and family from his enchantments, and never attack Dyfed again. His motive is revealed as vengeance for his friend Gwawl, Rhiannon's rejected suitor. All ends happily with the family reunited, and Dyfed restored.
Interpretation as a goddess
When Rhiannon first appears she is clearly a magical figure arriving as part of the Otherworld tradition of Gorsedd Arberth. Her paradoxical style of riding slowly, yet unreachably, is strange and magical, though the paradox also occurs in mediaeval love poetry as an erotic metaphor. Rhiannon produces her "small bag" which is also a magical paradox for it cannot be filled by any ordinary means. When undergoing her penance, Rhiannon demonstrates the powers of a giantess, or the strength of a horse, by carrying travellers on her back.
As well as the possible inheritance from Epona noted earlier, Rhiannon also connects linguistically to Brittonic Rigantona. The suffix -on means divinity, and the initial rhi- or ri- means a ruler. Both names therefore mean 'Divine Queen' or 'Divine Ruler.' This latter is the same meaning as Teyrnon's name.
Rhiannon is also connected to three mystical birds. The Birds of Rhiannon/ Adar Rhiannon appear in the Second Branch, in the Triads of Britain, and in Culhwch ac Olwen. In the latter, the giant Ysbaddaden demands them as part of the bride price of his daughter. They are described as "they that wake the dead and lull the living to sleep." All this suggests Rhiannon as an earlier goddess of Celtic polytheism.
W J Gruffydd’s book "Rhiannon" (1953) was an attempt to reconstruct the original story. It is mainly focused on the relationship between the males in the story, and rearranges the story elements too liberally for other scholars' preference, though his research is otherwise detailed and helpful. Patrick Ford suggests that the Third Branch “preserves the detritus of a myth wherein the Sea God mated with the Horse Goddess.” He suggests “the mythic significance may well have been understood in a general way by an eleventh century audience.” Similar euhemerisms of pre-Christian deities can be found in other medieval Celtic literature, when Christian scribes and redactors reworked older deities as more acceptable giants, heroes or saints. In the Táin Bó Cúailnge, Macha and The Morrígan similarly appear as larger-than-life figures, yet never described as goddesses.
Proinsias Mac Cana's position is that "[Rhiannon] reincarnates the goddess of sovereignty who, in taking to her a spouse, thereby ordained him legitimate king of the territory which she personified." Miranda Jane Green draws in the international folkore motif of the Calumniated Wife, saying "Rhiannon conforms to two archetypes of myth ... a gracious, bountiful queen-goddess; and ... the 'wronged wife', falsely accused of killing her son."
A striking example of modern Rhiannon inspiration is the Fleetwood Mac song "Rhiannon" on their debut album. Stevie Nicks has often recalled in interviews how she was struck with profound inspiration to create the song, based on a popular novel, though she had little accurate knowledge of the original Rhiannon. The song does not conflict with the canon, and quickly became a musical legend.
In artworks Rhiannon has inspired some entrancing images. A notable example is Alan Lee 1987, and 2001, who illustrated two major translations of the Mabinogi, and his pictures have attracted their own following.
Rhiannon has a growing and varied tradition across the modern Pagan, Goddess, and Celtic tradition communities since the 1970s. While almost always sincere, such faith communities often base their devotions on a superficial knowledge which can be seriously in contradiction with the original. Depictions of Rhiannon can make her seem insipid, a wispy doll, elfin in a Victorian flower fairy way; which her arrogant and even ruthless mediaeval source does not support. Rhiannon is not all loving and motherly, as her innocent victim Gwawl might attest. Where a literary assessment can include her ruthless and strategic complexity, a poetic yearning akin to other Celtic Mist traditions, finds a gentler, more idealised Celtic madonna.
- Celtic Polytheism
- The Mabinogi has also been known as the Mabinogion
- Rhiannon, song by Stevie Nicks and Fleetwood Mac
- Welsh Literature
- Welsh mythology
- Welsh mythology in popular culture
- Llyfr Gwyn/ The White Book of Rhydderch
- Llyfr Goch/ The Red Book of Hergest
- e.g. Sioned Davies (trans.), The Mabinogion, Oxford 2007, p. 231.
- Gruffydd, W. J. Rhiannon: An Inquiry into the Origins of the First and Third Branches of the Mabinogi
- Hutton, Ronald (2014). Pagan Britain. Yale University Press. p. 366. ISBN 978-0300197716.
- The Mabinogion. Davies, Sioned. 2005.
- Patrick K Ford, The Mabinogi and Other Medieval Welsh Tales (1977)
- Mac Cana, p. 56.
- Green, p. 30.
- Sullivan, Charles William III. “Conscientious Use: Welsh Celtic Myth and Legend in Fantastic Fiction.” Celtic Cultural Studies, 2004. http://www.celtic-cultural-studies.com/papers/04/sullivan-02.html
- William J. Gruffydd (1953). Rhiannon. Cardiff.
- Jones, Gwyn and Jones, Thomas. "The Mabinogion ~ Medieval Welsh Tales." (Illust. Alan Lee). Dragon’s Dream., 1982.
- Guest, Charlotte. "The Mabinogion." (Illust. Alan Lee). London and NY.: Harper Collins., 2001.
- MacKillop, James (2004). "Rhiannon" in A Dictionary of Celtic Mythology. Oxford University Press. ISBN 9780198691570
- Sullivan, Charles William III. “Conscientious Use: Welsh Celtic Myth and Legend in Fantastic Fiction.” Celtic Cultural Studies, 2004. 
- Parker, Will. “Mabinogi Translations.” Mabinogi Translations, 2003. Reliable online text extremely useful for fast lookup, or copying quotes. http://www.mabinogi.net/translations.htm