Olive Hornby's brother

Mr Hornby was the brother of Olive Hornby. Moaning Myrtle showed up uninvited at his wedding because she was haunting Olive, his sister, and apparently made a scene to remind Olive of the bullying she put up with when she was still alive. It was so big of a mess that Olive had to get help from the Ministry of Magic in getting rid of the ghost.

Notes and references
Mr Hornby Pan Hornby