Room of Requirement
| Location | 7th floor corridor, Hogwarts School of Witchcraft and Wizardry |
| Owners | Hogwarts School |
Sometimes known as the Come and Go Room, the Room of Requirement was an Unplottable room that could transform into anything someone needed. It was concealed, opposite a tapestry of Barnabas the Barmy, and to summon it you needed to walk past three times and think about what was needed.
The room was chosen as the headquarters for Dumbledore's Army in 1995 after Dobby suggested it.
The room was also used by Draco Malfoy in 1996-97 to repair the Vanishing Cabinet, which allowed the Death Eaters to enter the school and attack. Following this, a handful of students used the room to hide from the Death Eaters during the 1997-98 school year, and created a new passage to Hogsmeade so they could acquire food.
One iteration of the Room of Requirement was the Room of Hidden Things, which appeared to people who needed to hide things. This was where Ravenclaw's Diadem horcrux was hidden by Tom Riddle, and it had to be found by manually searching, as Summoning Spells did not work.
The room was thought to have been destroyed after Crabbe cast Fiendfyre in the room and razed the contents in 1998, which destroyed the diadem horcrux. However, the room has successfully been accessed since.