Abeloth, also known as the Bringer of Chaos, was a being who was very powerful in the dark side of the Force.
She first lived as the Servant, a mortal woman who served the powerful Ones on a unknown jungle planet over a hundred thousand years before the Battle of Yavin. But over the course of her life, she became the Mother: she kept the peace between the Father's warring Son and Daughter, and became a loving part of the family. But she was still mortal - she grew old while her ageless family lived on - and she feared that she would lose her precious family.
In a desperate attempt to hold onto the life she so loved, the Mother did the Forbidden - she drank from the Font of Power and bathed in the Pool of Knowledge. Her actions corrupted her, transforming the Mother into the twisted, immortal entity known as Abeloth.