Morgan goes by many names, the most popular being Morgana. As her name "Fay" suggests, she is a magical being. She is a great sorcerer, a healer, who uses her magic against her brother.
Morgan is the daughter of Igraine and her first husband Gorlois, Duke of Cornwall. This makes her Arthur's half-sister. She is married to King Uriens and is the mother of Yvain. In later works, she is the mother of Mordred.
The earliest mention of Morgan was by Geoffrey of Monmouth in his lesser known work Vita Merlini (The Life of Merlin). In this account, Morgan and her nine magical sisters reside in Avalon. They can only use their magic for good. But by the 13th Century, Morgan takes on a more sinister role.
It is in Lancelot-Grail where her character first takes a turn for the worse. Suddenly, instead of being this caring and compassionate woman who can only do good, she becomes this evil sorcerer, who is intent on bringing Artur and his kingdom down.
Morgan believes that Arthur ruined her life. To find out why we need to look at how Arthur was conceived...
Uther Pendragon became obsessed with Igraine, Morgan's mother. Uther is determined to have her in his bed. While Morgan's father, Glorious, is a way in battle, Uther Pendragon disguises himself - with the aid of Merlin - and tricks Igraine into thinking she is making love to her husband when in fact she is being raped by Uther. It is on this night that Arthur is conceived.
After her father's death, Morgan is spirited away to a convent ~ she is out of sight, out of mind. It is at the convent where Morgan begins to study magic. Later, her education is continued under the watchful eye of Merlin. However, Arthur puts a stop to her learning by marrying her off to King Urien of Gore. Their marriage is not a happy one, and Morgan takes a string of lovers until the fateful day when Queen Guinevere finds out about her not so honourable behaviour and puts a stop to it.
Morgan's relationship with Merlin also rapidly breaks down, and she ends up despising him too. To make matters worse, all her attempts at bringing Arthus's reign down is hampered by Nimue ~ The Lady of the Lake.
And then one day Lancelot comes to court. Poor Morgan, she falls head over heels in love with him, but alas he does not love her back. She tries countless times to seduce him and to trick him into loving her. Unfortunately, he is faithful to his lover, Guinevere. Morgan find's our about the affair and does everything she can to expose it.
In Post-Vulgate Queste Morgan is devoted to her magic. She even takes herself away from society, living in a forest. She becomes a shape-shifter - she can transform into any animal - and she earns the name Morgan the Goddess.
In Thomas Malory Le Morte d'Arthur, Morgan dedicates her life to bringing Arthur and Guinevere down.
In the tale of Gawain and the Green Knight, Morgan is the brains behind the plot. She wants to test the knights metal and, in an underhanded way, hopes to frighten the living daylights out of Guinevere!
Morgan's tale is told in a thousand different ways through the ages. The most recent account of Morgan's escapades can be found in the BBC series, Merlin. Here she goes by the name Morgana. She is a sorcerer. She is also Merlin's enemy and Arthur's half-sister ( although this time, they have the same father), and she lives in a world where magic is banned.
So from Welsh myth to an Arthurian one, Morgan goes on one heck of a journey. But the common theme throughout seems to be that she was dealt a poor hand which makes her one very bitter lady with a grudge.