The white lady of Berry Pomeroy Castle is assumed to be the spirit of Lady Margaret Pomeroy. She came to an unpleasant end at the hand of her extremely jelous twin sister Eleanor. Her sister was driven mad by the fact they were both in love with the same man. She had Margaret imprisoned in the now called St Margaret's tower. She was locked away and allowed to starve to death.
The white lady is seen all over the castle. She fills the individual who sees her with dread as tradition has it if you see her, your own imminent demise is close to hand.