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Morrigan was a famous Irish pure-blood witch, notable for being an Animagus who could turn into a crow.
Morrigan was an ancestor of William Sayre, who nicknamed his daughter, Isolt, "Morrigan" due to her affinity for all things natural when she was young.
According to Irish mythology, the Morrígan ("phantom queen") or Mórrígan (moe-ree-gan) ("great queen") was a figure associated with fate, especially with foretelling doom and death in battle — in this capacity, she would take the shape of a crow, flying above the battlefield.