The Prefects' Bathroom

• Type: Bathroom, Special Amenity
• Location: Fifth floor of Hogwarts Castle, Scotland. The entrance is the fourth door to the left of a statue of Boris the Bewildered.
• Owner/Residents: Hogwarts School of Witchcraft and Wizardry. It is for the exclusive use of school Prefects, the Head Boy, the Head Girl, and Quidditch captains. The ghost Moaning Myrtle is also a frequent visitor.
• Key Features: Password-protected entrance, vast marble interior, a swimming-pool-sized bath with numerous magical taps.

The Prefects' Bathroom is a luxurious and private bathing facility provided as a special privilege for students holding positions of responsibility at Hogwarts. Access is granted via a specific door on the fifth floor which has no handle, only a small scratch. Entry requires the correct password; the password given to Harry Potter in his fourth year was “pine fresh”. The interior of the bathroom is described as stunningly beautiful, brightly lit by a large candle-filled chandelier. The room is constructed entirely of gleaming white marble. The centerpiece is a large, rectangular, sunken bath that resembles a small swimming pool, complete with a diving board at one end. The bath is equipped with approximately one hundred different golden taps arranged around its edge, each of which dispenses water mixed with a unique type of magically-produced foam, bubbles, or scent. One tap, for example, releases “heaps of foamy, rose-scented bubbles,” while another creates thick, blue bubbles that are difficult to see through. The room also contains a stack of fluffy white towels, white linen curtains, and a single painting on the wall. This painting depicts a beautiful, blond-haired Mermaid sleeping on a rock in the sea. The Mermaid in the portrait is sentient and has been known to interact with the bathroom's occupants.

The Prefects' Bathroom is the setting for two significant events in Harry Potter's school career.

• In Harry Potter and the Goblet of Fire, Cedric Diggory advises Harry to take the Golden Egg to the bathroom to solve its clue, repaying Harry for his warning about the dragons. With the help of Moaning Myrtle, Harry submerges the egg in the water, which allows him to hear the Merpeople's song clearly. This reveals the nature of the Second Task of the Triwizard Tournament: to rescue something important from the Great Lake within a one-hour time limit.
• In Harry Potter and the Half-Blood Prince, the bathroom is the site of a violent duel between Harry and Draco Malfoy. Harry discovers a distraught Malfoy crying to Moaning Myrtle, overwhelmed by the task assigned to him by Lord Voldemort. Their confrontation quickly escalates into a duel. When Malfoy attempts to use an Unforgivable Curse, Harry retaliates with an unknown spell from the Half-Blood Prince's textbook: Sectumsempra. The curse inflicts deep, bleeding gashes on Malfoy, nearly killing him. Severus Snape arrives, heals Malfoy's wounds with a counter-curse, and assigns Harry detention for the remainder of the school year, causing him to miss the final Quidditch match. This event forces Harry to hide the dangerous textbook in the Room of Requirement.

• In the film adaptation of Harry Potter and the Goblet of Fire, the bathroom is depicted with large, elaborate stained-glass windows, one of which features a prominent image of a Mermaid. This visual element serves as a direct clue for the audience about the secret of the Golden Egg. (film)
• The location is an explorable area in the Lego Harry Potter video games, where players can interact with the magical taps. (video game)