Lot married Morgawse, daughter of Igraine and Gorloïs, at the same time Uther Pendragon married Igraine. The father of Gawaine, Agravaine, Gaheris, and Gareth, Lot was one of the rebel kings at the beginning of Arthur's reign. He showed himself a good strategist during the battle of Bedegraine:

Then all the eleven [rebel] kings drew them together, and then said King Lot, Lords, ye must other ways than we do ... ye may see what people we have lost, and what good men we lose, because we wait always on these foot-men, and ever in saving of one of the foot-men we lose ten horsemen for him; therefore this is mine advice, let us put our foot-men from us, for it is near night, for the noble Arthur will not tarry on the foot-men, for they may save themselves, the wood is near hand. And when we horsemen be together, look every each of you kings ... that none break upon pain of death. And who that seeth any man dress him to flee, lightly that he be slain, for it is better that we slay a coward, than through a coward be slain.

Acting upon Lot's advice, the kings at least saved themselves, though not the battle.

After Bedegraine, Lot's wife Morgawse came to Arthur's court, "in manner of a message, but she was sent thither to espy the court." Although we know from the Vulgate account that Morgawse did not share Lot's enmity against Arthur, from Malory's account it appears that at this point Lot was sounding Arthur out, leaving himself free to opt for either piece or further rebellion according to Arthur's strength and disposition.

Unfortunately, Arthur begat Mordred on Morgawse and later, learning that a boy born on May Day would destroy him, had Mordred, along with all the other lords' sons born about that time, put on a ship and sent out to sea to die. Whether Lot knew that Arthur had cuckolded him, or whether he belived Mordred - apparently killed with the other babies - to have been his own son, his enmity against Arthur was now cemented, and he joined Ryence and Nero as ringleaders of the second rebellion of twelve kings.

This time the crucial battle was fought before Terrabil Castle. During the first part of the battle, Merlin cunningly

came to King Lot ... and held him with a tale of prophecy, till Nero and his people were destroyed.

Learning too late of their destruction, Lot cried,

Alas ... I am ashamed, for by my default there is many a worshipful man slain. ... Now what is best to do? ... whether is me better to treat with King Arthur or to fight, for the greater part of our people are slain and destroyed? Sir, said a knight, set on Arthur for they are weary and forfoughten and we be fresh. As for me said King Lot, I would every knight do his part as I would do mine.

So he went into battle and was killed by King Pellinore [though there must have been some confusion, for Pellinore's son Lamorak later claimed it had been Balin who dealt the fatal stroke].

There is an almost Grecian fate about Lot's death. Merlin had known that either Arthur or Lot must die at Terrabil that day, and preferred it be Lot, yet even Merlin regretted the necessity. "Alas he might not endure", says Malory, "the which was great pity, that so worthy a knight as [Lot] was should be overmatched". All the rebel kings died in the battle, and Arthur buried them all with full honors in St. Stephen's Church in Camelot.

But of all these twelve kings King Arthur let make the tomb of King Lot passing richly, and his tomb by his own ...

Chrétien de Troyes places King Lot among Arthur's living knights in the list beginning line 1691 of Erec and Enide, and identifies him as Gawaine's father in Yvain and Perceval.

Lot may also have been the father of Thenew, and thus the grandfather of Saint Kentigern.