Moaning Myrtle is a ghost in Hogwarts, who can usually be found haunting the girls' bathroom on the second floor. Myrtle constantly wails, moans and sobs, especially when anyone mentions her death to her, and her dreadful moods can often affect the plumbing and flood the bathroom. She was killed in the same bathroom she now haunts by the basilisk in 1943, when Tom Riddle opened the Chamber of Secrets for the first time.
 Second Book
Harry, Ron and Hermione first encounter Moaning Myrtle in the second book, when the trio use Myrtle's bathroom as a place to secretly brew polyjuice potion. In this book it is learnt that Myrtle was a student at Hogwarts fifty years ago who had hidden in the girls' bathroom to escape Olive Hornby, a fellow student who had been teasing Myrtle about her glasses. Whilst in the bathroom, the Chamber of Secrets was opened, the Basilisk escaped and Myrtle died by looking into its eyes. She had been haunting the same bathroom ever since. Tom Riddle used her murder to create his first horcrux: the diary
 Fourth Book
Whilst in the prefect's bathroom trying to solve the mystery of the golden Egg, Harry encounters Myrtle again, who makes flirtatious and lascivious comments to Harry. Myrtle helps Harry by telling him to open the egg underwater, leads him to solve the mystery.
 Sixth Book
In the sixth book, Myrtle becomes friendly with Draco Malfoy, who spends a lot of time crying in the bathroom. When Harry injures Malfoy by using the Sectumsempra curse on him, Myrtle spreads the news by screaming "MURDER! MURDER IN THE BATHROOM!"
 Film Portrayals
Moaning Myrtle is portrayed in the second and fourth films by Shirley Henderson. Her role is not reprised in the sixth film.