In Arthurian legend, Sir Kay (Welsh: Cai, Middle Welsh Kei or Cei; Latin: Caius; French: Keu; French Romance: Queux; Old French: Kès or Kex) is King Arthur's foster brother and later seneschal, as well as one of the first Knights of the Round Table. In later literature he is known for his acid tongue and bullying, boorish behaviour, but in earlier accounts he was one of Arthur's premier warriors. Along with Bedivere, with whom he is frequently associated, Kay is one of the earliest characters associated with Arthur. Kay's father is called Ector in later literature, but the Welsh accounts name him as Cynyr Ceinfardqfog.
Cai or Cei is one of the earliest characters to be associated with the Arthurian mythology, appearing in a number of early Welsh texts, including Culhwch ac Olwen, Geraint fab Erbin, Iarlles y Ffynnon, Peredur fab Efrawg, Breuddwyd Rhonabwy, Pa Gur, and the Welsh Triads. His father is given as Cynyr Ceinfarfog (Fork-Beard), his son as Garanwyn and his daughter as Kelemon.
Before Cai's birth, Cynyr prophesied that his son's heart would be eternally cold, that he would be exceptionally stubborn, and that no one would be able to brave fire or water like him. Cai is attributed with a number of further superhuman abilities, including the ability to go nine days and nine nights without the need to breathe or to sleep, the ability to grow as "tall as the tallest tree in the forest if he pleased" and the ability to radiate supernatural heat from his hands. Furthermore, it is impossible to cure a wound from Cai's sword. Cai is killed by Gwyddawg fab (son of) Menestyr, who is in turn killed in vengeance by Arthur.
Robert Graves commented that the early description of Kai "is close to the account given of the Sun-hero Cuchulain in his battle rage. But in the later Arthurian legends Kai has degenerated into a buffoon and Chief of Cooks" - an aspect of the folklore process whereby old heroes must be downgraded (but not forgotten) in order to make room for new.
One of the earliest direct reference to Cai can be found in the 10th-century poem Pa Gur, in which Arthur recounts the feats and achievements of his warriors so as to gain entrance to a fortress guarded by Glewlwyd Gafaelfawr, the titular porter. The poem concerns itself largely with Cai's exploits:
Prince of the plunder, / The unrelenting warrior to his enemy; / Heavy was he in his vengeance; / Terrible was his fighting.
When he would drink from a horn, / He would drink as much as four; / When into battle he came / He slew as would a hundred.
Unless God should accomplish it, / Cei's death would be unattainable.
Worthy Cei and Llachau / Used to fight battles, / Before the pain of livid spears [ended the conflict].
On the top of Ystarfingun / Cei slew nine witches. / Worthy Cei went to Ynys Mon / To destroy lions. / Little protection did his shield offer / Against Palug's Cat.
Culhwch's father, King Cilydd son of Celyddon, loses his wife Goleuddydd after a difficult childbirth. When he remarries, the young Culhwch rejects his stepmother's attempt to pair him with his new stepsister. Offended, the new queen puts a curse on him so that he can marry no one besides the beautiful Olwen, daughter of the giant Ysbaddaden. Though he has never seen her, Culhwch becomes infatuated with her, but his father warns him that he will never find her without the aid of his famous cousin Arthur. The young man immediately sets off to seek his kinsman. He finds him at his court in Celliwig in Cornwall and asks for support and assistance. Cai is the first knight to volunteer to assist Culhwch in his quest, promising to stand by his side until Olwen is found. A further five knights join them in their mission. They travel onwards until they come across the "fairest of the castles of the world", and meet Ysbaddaden's shepherd brother, Custennin. They learn that the castle belongs to Ysbaddaden, that he stripped Custennin of his lands and murdered the shepherd's twenty-three children out of cruelty. Custennin set up a meeting between Culhwch and Olwen, and the maiden agrees to lead Culhwch and his companions to Ysbadadden's castle. Cai pledges to protect the twenty-fourth son, Goreu with his life. The knights attack the castle by stealth, killing the nine porters and the nine watchdogs, and enter the giant's hall. Upon their arrival, Ysbaddaden attempts to kill Culhwch with a poison dart, but is outwitted and wounded, first by Bedwyr, then by the enchanter Menw, and finally by Culhwch himself. Eventually, Ysbaddaden relents, and agrees to give Culhwch his daughter on the condition that he completes a number of impossible tasks (anoethau), including hunting the Twrch Trwyth and recovering the exalted prisoner Mabon ap Modron.
Cai is a prominent character throughout the tale and is responsible for completing a number of the tasks; he kills Wrnach the Giant, rescues Mabon ap Modron from his watery prison and retrieving the hairs of Dillus the Bearded. However, when Arthur makes a satirical englyn about Cai, he grows angry and hostile towards the king, ultimately abandoning the quest and his companions. The narrative tells us that Cai would "have nothing to do with Arthur from then on, not when the latter was waning in strength or when his men were being killed." As a result, he did not take part in the hunt for Twrch Trwyth.
In the Life of St. Cadoc (c.1100) Bedwyr is alongside Arthur and Cai in dealing with King Gwynllyw of Gwynllwg's abduction of St. Gwladys from her father's court in Brycheiniog. Cai appears prominently in the early Welsh version of Tristan and Isolde, in which he assists the two lovers and is himself infatuated with a maiden named Golwg Hafddydd, and in the early dialogue poems relating to Melwas' abduction of Gwenhwyfar. The context suggests that Cai is rescuing the queen from the otherworldly suitor, and may imply a romantic relationship between Cai and Gwenhwyfar.
The Welsh Triads name Cai as one of the "Three Battle-Diademed Men of the Island of Britain" alongside Drystan mab Tallwch and Hueil mab Caw. In the Triads of the Horses, his horse is named as Gwyneu gwddf hir (Gwyneu of the Long Neck). According to tradition, Cai is intimately associated with the old Roman fort of Caer Gai.
In the Welsh Romances (specifically Owain, or the Lady of the Fountain and Peredur son of Efrawg), Cai assumes the same boorish role he takes in the continental romances. However, manuscripts for these romances date to well after Chrétien de Troyes, meaning that Cai as he appears there may owe more to Chrétien's version of the character than to the indigenous Welsh representation.
Kay and Bedivere both appear in Geoffrey of Monmouth's Historia Regum Britanniae, and support Arthur in his defeat of the Giant of Mont Saint-Michel. Geoffrey makes Kay the count of Anjou and Arthur's steward, an office which he holds in most later literature. In Chrétien de Troyes's Erec and Enide, a son Gronosis is mentioned, who is versed in evil. By contrast, the Welsh attribute to him a son and daughter named Garanwyn and Celemon. Romance literature rarely deals with Kay's love life, with one exception being Girart d'Amiens' Escanor, which details his love for Andrivete of Northumbria, whom he must defend from her uncle's political machinations before they can marry.
In the works of Chrétien, Kay assumes the characteristics with which he is most associated today: hot-headedness and fiery temper (retained from the Welsh literature), supplemented by his role as an incompetent braggart. Chrétien uses him as a scoffer and a troublemaker; a foil for heroic knights including Lancelot, Ywain, or Gawain. He mocks the chivalric courtesy of Sir Calogrenant in Yvain, the Knight of the Lion, and he tricks Arthur into allowing him to try to save Guinevere from Maleagant in Lancelot, the Knight of the Cart, which ends in his humiliating defeat. In Perceval, the Story of the Grail, Sir Kay grows angry with Perceval's naïveté and slaps a maiden who says he will become a great knight; Perceval later avenges her by breaking Kay's shoulder. Wolfram von Eschenbach, who tells a similar story in his Parzival, asks his audience not to judge Kay too harshly, as his sharp words actually serve to maintain courtly order: "Though few may agree with me - Keie was a brave and loyal man...The mighty Keie."
Kay is ubiquitous in Arthurian literature but he rarely serves as anything but a foil for other characters. Although he manipulates the king to get his way, his loyalty to Arthur is usually unquestioned. In the Vulgate Cycle, the Post-Vulgate and Thomas Malory's Le Morte d'Arthur, Kay's father Ector adopts the infant Arthur after Merlin takes him away from his birth parents, Uther and Igraine. Ector raises the future king and Kay as brothers, but Arthur's parentage is revealed when he draws the Sword in the Stone at a tournament in London. Arthur, serving as squire to the newly knighted Kay, is locked out of the house and cannot get to his brother's sword, so he uses the Sword in the Stone to replace it. Kay shows his characteristic opportunism when he tries to claim it was in fact he that pulled the sword from the stone, not Arthur, making Kay the true King of the Britons, but he ultimately relents and admits it was Arthur. He becomes one of the first Knights of the Round Table, described as "best worthy to be a knight of the Round Table of any", and serves his foster-brother throughout his life.
Scholars have pointed out that Kay's scornful, overly boastful character never makes him a clown, a coward or a traitor, except in the Grail romance Perlesvaus, in which he murders Arthur's son Loholt and joins up with the king's enemies. This strange work is an anomaly, however, and Kay's portrayal tends to range from merely cruel and malicious, as in the Roman de Yder or Hartmann von Aue's Iwein to humorously derisive and even endearing, as in Durmart le Gallois and Escanor.
Despite his ubiquity, Kay's death is not a frequent subject in the Arthurian canon. In Welsh literature, it is mentioned he was killed by Gwyddawg and avenged by Arthur. In Geoffrey of Monmouth and the Alliterative Morte Arthure, he is killed in the war against the Roman Emperor Lucius, while the Vulgate Cycle describes his death in France, also in battle against the Romans. According to Malory's Book 5, Kay does not die in the war against Rome, but rather survives and later is part of a party sent to try and retrieve Excalibur's sacred scabbard, prior to the Battle of Camlann. He is also among the few people who survives the battle of Camlann, although it is ambiguous as to how he does so; in later interpretations it is suggested that he never participated in that battle.