Morgana Le Fey (b. April 5, 499-d. July 15, 800), is a half-blood witch and the second most powerful magical being to ever live-- the first being Merlin Emrys. She attended Hogwarts between 510-518 and was sorted into Ravenclaw House. She went on to assist her brother Arthur in conquering all the lands of Albion and bringing peace to the lands.
Morgana was the illegitimate child of Uther Pendragon and Vivienne Le Fey--the wife of Uther's closest friend. Therefore, the affair was kept secret and Morgana was said to be Gorlois Le Fey's daughter who was born while he was off fighting a war. Vivienne died in childbirth, and Morgana was taken care of by both her step-father and elder half-sister Morgause. As a result of this, Gorlois--who did not know of the betrayal--raised and loved Morgana as his own. The two were very close when Morgana was young. So much so that, when he died, Morgana sealed herself in her room for weeks and cried.
As six-years-old, now supposedly an orphan, Uther took Morgana in as his ward while claiming that it was the last request of his late friend Gorlois. It was at this time that she first met and grew close to her elder half-brother Arthur. Though the two often argued, typically about Morgana's skill with swords being superior to Arthur's own, they quickly grew to be nearly inseparable.
Unfortunately, accidental magic often happened around Morgana. When she realized that she was causing it, she grew terrified. Uther was the king who began the Great Purge to exterminate all magic in Camelot, and he executed anyone who he suspected of possessing magic. Morgana was certain that he would kill her if he discovered her powers.
Arthur attended Hogwarts without telling either Uther or Morgana two years before Morgana herself was set to attend. Godric Gryffindor, who had come to collect Morgana for schooling, enchanted Uther to make him think that he was sending his children off to a prestigious school very far away.
At Hogwarts, Morgana quickly befriended a young boy named Merlin who was in the same year as her. The two became nearly inseparable and often studied together in their advanced classes.