The Grey Lady is a ghost. She is in fact one of the most famous in the whole of Hogwarts. When alive, her name was Helena Ravenclaw and she was the daughter of the founder Rowena Ravenclaw. She lived be-tween around 982 and 1000. She of course, became the House ghost for Ravenclaw.

The story goes that in around 996/1000 she stole her mother’s diadem (now famous to us but not then) and ran off to Albania. This is where she died. Her betrayal to her mother caused a great wound. I wonder if she blamed herself for her mother becoming ill and eventually dying. I see it as a possibility.

Helena was loved by the Baron (of Slytherin house) but she would forever reject his advances. I think that what she wanted to find was a true and honest love and that just wasn’t him.