Morgause

In the best-known versions of the legend, he is the son of Arthur's sister Morgause and King Lot of Orkney and Lothian.

The theme of illegitimate conception is repeated in Arthur's siring of Mordred by his own half-sister Morgause in the 13th century French prose cycles, which was invented by them; it is Mordred who mortally wounds King Arthur in the Battle of Camlann.

He was the youngest son of King Lot and Queen Morgause, King Arthur's half-sister, thus making him Arthur's nephew, as well as brother to Gawain, Agravain, and Gaheris, and either a brother or half-brother of Mordred.

He is generally depicted as the husband of Arthur's sister or half-sister, often known as Anna or Morgause.

He is the second eldest son of King Lot of Orkney with one of King Arthur's sisters known as Anna or Morgause, thus nephew of King Arthur, and brother to Sir Gawain, Gaheris, and Gareth, as well as half-brother to Mordred.

Later variants most often characterised him as Arthur's villainous bastard son, born of an incestuous relationship with his half-sister, the Queen of Orkney named either Anna, Orcades, or Morgause.

Different sorceresses known as the Lady of the Lake appear concurrently as separate characters in some versions of the legend since at least the Post-Vulgate Cycle and consequently the seminal Le Morte d'Arthur, with the latter describing them as a hierarchical group, while some texts also give this title to either Morgan or her sister.

In Thomas Malory's Le Morte d'Arthur, her daughters by Gorlois are Elaine, Morgause and Morgan le Fay.

An important episode is Gawain's liberation of a castle whose inhabitants include his long-lost mother (see Morgause), his grandmother Ygerne and his sister Clarissant, whose existence was unknown to him.

A nephew of King Arthur, Gaheris is the third son of Arthur's sister or half-sister Morgause and her husband Lot, King of Orkney and Lothian.