Lady of the Lake
The Lady of the Lake is the original owner of the sword Excaliburn, until she placed it into a stone in which only the king could pull it out. She is also Sir Loungelot's mother, and gave Loungelot up to King Allfire as he was not a good son.

In the episode Excaliburn, when Allfire thought he couldn't pull Excaliburn from the stone, he searched for the Lady of the Lake, but ended up at the wrong lakes, meeting the Princess of the Pond, the Female of the Fjords, the Wench of the Whirlpool, the Babe of the Bay, and the Dame of the Dam. When he saw Princess Flame later on, he initially thought she was the Lady of the Lake. The Lady of the Lake never actually appears in this episode.

In Excalibroke, Flicker and Loungelot went to see the Lady of the Lake when Loungelot accidentally broke Excaliburn. The Lady of the Lake claimed that Loungelot had not renewed the warranty, and that he must undertake three tests in order to fix it. These tests turned out to be a setup so that Loungelot could join the choir with his brother Murray, but in the end Excaliburn was struck by lightning (presumably caused by the Lady of the Lake) to fix it.