Morgana Le Fay
Morgana was once a high priestess of the goddess Gaea and a sorceress of no mean talent in ancient Atlantis, some 40,000 years ago. Her mother was a demigoddess of the New Gods, named Igraine.
Even by the standards of Atlantis, Morgana was haughty, proud, and arrogant. She tampered frequently with powers that the Atlantean Council forbade, including temporal manipulation and mind control. Much of her early life was spent under the influence of the dangerous immortal Vandal Savage, who indulged her cruel streaks and experimentation. She had a softer side, however, and upon her wanderings through the Astral Plane, she would encounter the hoary mists of Faerie. They would become crucial allies in the millennia yet to come.
Upon learning of the existence of the forbidden Realm Between Worlds, Morgana became obsessed with the Old Ones. They seemed an avenue of power to conquer the gleaming Atlantean city of R'lyeh. At Savage's behest, she attempted to open a gate and compel a minor Old One into serving her. This created a rupture into the Realm Between Worlds and almost allowed a monstrous entity into reality. Atlantean mages repelled the creature and sealed the breach. Abandoned by Savage, Morgana fled Atlantis bare steps ahead of a death squad. She found herself in Otherworld shortly thereafter, in the company of Merlyn, the immortal Magician.
Her asylum would turn to an apprenticeship, then to intimacy. Merlyn and Morgana walked the realms of Yggdrasil, meeting many races. Her close alliance with the Faerie would create a deep rapport with the Tuatha de Danaan. Enlisting the help of the Fae in defending the Outer Gates to the Realm Between Worlds, she inspired the creation of the High Courts of the Seelie and Unseelie-- Summer and Winter, eternal guardians for Otherworld and all reality. During a prolonged assault on Faerie, Morgana led many of the survivors of the carnage to The Nine Realms. There, they settled in Alfheim, and survivors of the Seelie courts became known as Light Elves and Dark Elves.
In 38,000 BCE, Morgana's lust for power overtook her patience. She engaged with her former lover Vandal Savage and launched a campaign to conquer Otherworld. She reached into the Realm Between Worlds and drew forth a strange stone. The High Goddess Brigid, of the Tuatha de Danaan, forged it into a blade, which Morgana gave to Vandal Savage. This blade was unique beyond all measure, as one of the few weapons that could slay any immortal. In a rare direct action, Vandal led the Seelie armies in an assault on the Starlight Citadel. Merlyn's power, magnified threefold by the Vishanti, crushed vast numbers of the Seelie with little effort. All was done in a bid to buy Savage a single opportunity to strike, and his blow was nearly a mortal one. Prepared to finish Merlyn off, he was attacked by a suddenly repentant Morgana. This gave Merlyn the moment he needed to marshal his defense and blast Vandal back to Earth, flinging him unprotected through the dimensions.
Weakened, Merlyn was forced to withdraw to the Starlight Citadel. There, at the peak of Otherworld, he was truly unassailable. Momentarily content with her conquest, Morgana set about appointing herself the new ruler of Otherworld. The Fae were encouraged to repopulate Otherworld, and eventually the harmony of that dimension changed to the point that the ancient home of the Fae Folk-- Tir na Nog-- manifested next to the island of Avalon. Morgana became something less human, turning into a Fae Folk herself.
Never forgetting her ancient enmity with Atlantis, Morgana spent millennia waiting for the right opportunity to exact her revenge. Her machinations became more subtle over time; Atlantis was too powerful to confront directly.
Her moment came when Atlantis was facing Ragnarok-- the Cataclysm of the death of the Demiurge. She traveled to her ancient home of R'lyeh and convinced a select group of Atlanteans that the Old Ones could protect them from the oncoming storm. So desperate were they that they gave her access to the lost relic known as the Cosmic Cube. In a moment when the Demiurge was at its weakest, when the forces of Atlantis were compromised and vulnerable and exposed, Morgana looked at R'lyeh and gave in to her anger and resentment. She used the Cube to smash through the walls between reality and open a Gate into the Realm Between Worlds, calling forth the ancient Great Old One known as C'thulu.
C'thulu promptly slaughtered hundreds of Atlantean mages and drove many others insane. The imbalance of his presence destroyed the careful architecture of the Atlantean survival strategy. It took all the collective life force of the Atlantean archmages and the last flickering power of the Demiurge itself to contain the monster, binding its awareness into the The Dreaming to silence it.
The nations of Atlantis were destroyed in a single day and night. So horrified was Morgana by her actions that she vowed never to open the Outer Gates again, and she watched as her home sank under the ocean and became known as the Sunken City Where C'thulu Sleeps.
With her powers badly sundered due to the collapse of the Demiurge, Morgana's immense magical talent was reduced to almost nothing. Still, she knew the secret Ways of the Fae Realms better than anyone, and would often use these backdoors to slip in and out of many dimensions across Yggdrasil's branching reach. She spent many centuries wandering Earth, looking for surviving Atlanteans and collecting fragments and artifacts that survived the cataclysm.
During the Hyborean Era she encountered the warriors Red Sonja and Conan The Barbarian. She would be frequently stymied by the duo for much of the Age of Barbarians.
In 10,000 BCE, the Cosmic Cube was used to repair the damage to the Demiurge. Morgana's powers returned haltingly. Far from the Fae Realms, she found herself increasingly outpaced by ambitious and talented Sorcerers Supreme appointed by the Vishanti to protect Earth. Rebuffed by the newly immortal Amazons of Themyscira, Morgana conspired with the Sorcerer Supreme called Semiramis of Nimrud. She encouraged Semiramis into luring the god Hercules to Earth to attack Themyscira and destroy the island nation. Semiramis refused to surrender her title to Morgana and instead attacked the other woman. Morgana was forced to flee to Otherworld.
In 600 AD, Morgana discovered that her mother, the demigoddess Igraine, had borne a son named Arthur Pendragon. Seducing her half-brother, Morgana gave birth to her own child-- Mordred. Her obsession with personal power was transferred to her son, whom she saw as the rightful heir to Britannia and the realms protecting Otherworld.
She would frequently undermine Arthur's efforts to protect Britannia, including stealing his legendary scabbard for Excalibur and flinging it into a tributary of the Fae Realms. Arthur's greatest knights-- Lancelot, Percival, and Galahad-- embarked on a great quest to capture the ancient book of the Darkhold, containing spells and incantations long coveted by Morgana. She intercepted the knights, and used it to summon Chthon, an ancient and malevolent Elder God to do her bidding. Instead it unleashed Chthon upon the world, and the mighty entity immediately struck out at Camelot-- the lock on the door to Otherworld, and therefore to the Vishanti and their power.
The combined efforts of the Knights of the Round, Merlyn, and Morgana herself were required to seal the entity away once more, under the peak of Mount Wundagore. Humiliated, Morgana withdrew to Otherworld once more, plotting and planning again how she might give her son the eternity of domination over man that she felt was his birthright.