King Arthur Pendragon (fl. 5th century – c. 537) was a Romano-British leader who led the defense of his people against the Anglo-Saxon invaders in the early 6th century. He was also a leader of the Order of the Ancients.
According to legend, Arthur possessed a sacred sword called Excalibur which he pulled from a stone as a young man that proved he was the Britons' true high king. Arthur also owned a mantle that allegedly had the ability to turn the user invisible. Arthur used Excalibur to rally his people as their newly-crowned king to fight in defense of their lands against the invading Anglo-Saxons. At some point following this, after forming the Knights of the Round Table, he had his sword placed within an ancient structure beneath Stonehenge with an accompanying note hoping that Excalibur would serve whomever found it next.
Arthur died under unclear circumstances after being betrayed by his wife, best friend, and son.
After his death, Arthur Pendragon became an important part of folklore all over England, such that countless places and peoples were said to have interacted with him, regardless the veracity of the claims. Indeed, as the Assassin Shaun Hastings observed in 2020, "In England, 'local lore' always gets back to Arthur somehow". In one notable example from the Viking expansion into England in the 9th century, the shieldmaiden Eivor Varinsdottir of the Raven Clan found a note during her travels claiming that Arthur once fought a woman by the name of Winniwulf Seaxdottir to a draw for the title of "Ruler of the Britons".
Later, Arthur's sword and note were retrieved by Eivor after gathering eleven tablet inscribed with depictions of the Treasures of Britain.
By the Industrial Revolution in the 19th century, a brewery had brewed a beer named after Arthur, which it called Merlin & Arthur Imperial Stout. In 2015, Shaun Hastings tasted this beer and then wrote a tasting note voicing his displeasure at it.
In 2012, Clay Kaczmarek included Walter Crane's illustration of Arthur pulling out the sword in the stone in a set of puzzles he had hidden within the Animus for his successor, Desmond Miles to find. Desmond did so in September of that year, uncovering Clay's message suggesting that the sword of Arthur was in fact a Sword of Eden.
In 2016, Alan Rikkin was of the opinion that Arthur's view of the Templars' role was idealistic and misguided, seeing his failure as proof that the Order was meant to follow a different path in the 21st century.
- Assassin's Creed II (appears in Glyphs only)
- Assassin's Creed: Syndicate (mentioned in Database entry only)
- Assassin's Creed: Heresy (mentioned only)
- Assassin's Creed: Valhalla (first identified as Arthur Pendragon)
- Assassin's Creed II – Glyph #5: "Instruments of Power"
- Assassin's Creed: Valhalla
- Assassin's Creed: Heresy – Epilogue
- Assassin's Creed: Valhalla – Database: Stiperstanas
- Assassin's Creed: Valhalla –  / Scroll Reeking of Lost Heroism
- Assassin's Creed: Syndicate – Database: Merlin & Arthur Imperial Stout
- Assassin's Creed: Initiates – The Desmond Files