Dina Gallager

Dina Gallager was a witch who had an affair with Albus Dumbledore, when he was married to Sheila Rookwood. The jealous Sheila killed Dina, and she became a ghost. The ghosts of Dinah, Anita, Lisa and Cassius kidnappe Sheila when she tried to kill Harry Potter and Hermione Granger. The four ghosts want to kill Sheila as revenge for her killing them in the past, but Sheila manages to escape.