Yes, in many versions of the Arthurian legend, King Arthur has a son, Mordred, through an incestuous relationship with his half-sister, Morgause (sometimes conflated with Morgan le Fay). This union is a pivotal, often tragic, element in the tales, leading to the downfall of Camelot, though the specifics (like whether they knew of their relation) vary by storyteller, notes Wikipedia and Reddit users.
Mordred is the only son of King Arthur. In most versions of the legend, Mordred's mother is Arthur's half-sister, making him a product of incest.
She is the biological daughter of Merlin and his wife Gwendolyn, but was stolen from her cradle as a baby, with the young Morgana left in her place as a changeling.
Arthur, who is no saint himself, has a child out of wedlock – the product of an incestuous union with his half-sister Morgause (in some versions of the legend it is Morgan, but the two have often been conflated, especially in more modern retellings).
Arthur and Guinevere were childless. Arthur had an illegitimate child, Mordred, but never a legitimate one. This was the tragedy of Camelot.
She is thought of as a very beautiful woman; however, her life was tragic, and she never seemed to achieve true happiness. Guinevere was often rescued by men and represents a true damsel in distress. Although she married King Arthur, she had an affair with Lancelot and loved him.
Lancelot「ランスロット」 is the son of Ban and Elaine, and the prince of the Kingdom of Benwick. He is also a Holy Knight of the Kingdom of Liones, and one of the Four Knights of the Apocalypse.
Merlin loves Arthur due to their intertwined destiny, where Merlin's magic exists to protect Arthur and guide him to become the great king he's fated to be, fostering a deep bond of friendship, loyalty, and profound care that evolves from obligation to genuine love, with some interpretations suggesting romantic love as well, especially given their willingness to sacrifice everything for each other.
Arthur was grateful for his aid and later made him a Knight of Camelot after he volunteered to help rescue Uther (The Coming of Arthur). Lancelot sacrificed himself in Arthur's place to banish the Dorocha, leaving Arthur deeply saddened.
Merlin (1889), is a verse play by Professor John Veitch, with only three characters: Merlin, "Gwendydd (The Dawn) - His twin sister", and "Hwimleian (The Gleam) - His early love".
In #Arthurian myth, Nimue, (aka Vivien, or the Lady of the Lake) refused to give Merlin her love until he taught her all his secrets & spells, after which she used against him by trapping him forever, either in the trunk of a hawthorn tree or beneath a stone.
However, Mordred's faith in Arthur and Camelot was shattered after the imprisonment and death of his beloved Kara. Believing that Arthur had betrayed him and metaphorically spat on their friendship, Mordred turned against the king and joined Morgana once more.
Just to clarify for any readers in case there was any confusion, the three wives of Arthur in Welsh tradition were indeed named Guinevere (or rather, Gwenhwyfar), but the three mistresses had their own names.
In addition, while Arthur is more conflicted than Uther, he does condone Uther's actions, and keeps up the same regime when he takes the throne. Lastly, Morgana feels betrayed by Arthur. Maybe she thought that Arthur ordered Merlin to poison her, or maybe it's just his overall stance towards magic in general.
Sir Lancelot was King Arthur's most trusted companion and loyal friend, but the closeness of their relationship made Lancelot's ultimate betrayal all the more painful.
He also played a central role in Malory's 15th-century prose work Le Morte Darthur, in which it was essentially the conflict between Lancelot's love for Guinevere and his loyalty to his lord that led to Arthur's “dolorous death and departing out of this world.”
They pointed out that it says in the Bible, "If a man shall take his brother's wife, it is an unclean thing; they shall be childless." If Catherine's marriage to Arthur had actually been consummated, her marriage to Henry would have been a sin, justifying an annulment.
Catherine recovered but Arthur died aged only 15 in 1502. Arthur was buried in Worcester Cathedral and his chantry, located to the right of the High Altar, near the tomb of King John, still survives.
Red hair, tall height, and light colored eyes seem to be notable family traits, though tall height seems to be more notable with the men. I think there is also some arguable resemblance between Arthur's surviving portraits and one of the few surviving portraits of a young Henry VIII.
Believed at first to be Ironside's son, Percival is later revealed to be a Life Spirit bound inside a human vessel by Ironside in an attempt to save his real son, Diodora.
Unlike so many other knights, Lancelot was not killed in battle. After being dismissed from Arthur's court, Lancelot became a monk and devoted himself to a quiet religious life to atone for his affair with Guinevere. Guinevere, in turn, became a nun.
He is known for his super resilience due to his time spent in Purgatory, and formerly, his immortality which he gave up in order to resurrect Elaine.