The Trophy Room is a room on the Third Floor of the Hogwarts Castle. Awards, trophies, cups, plates, shields, statues, and medals are kept in crystal glass displays in this room. This room also contains a list of Head Boys and Head Girls. Prominently displayed are Hogwarts Awards for Services to the School, with known recipients being Tom Marvolo Riddle, Harry Potter and Ron Weasley. Probably, in 1995, the Triwizard Cup was placed here as well. The Trophy Room is connected to an Armour Gallery.

The Third Floor Corridor on the right hand side was out of bounds during the 1991–1992 school year at Hogwarts School of Witchcraft and Wizardry because it was the access point to the Chambers where the Philosopher's Stone was being hidden. Fluffy, a three-headed dog owned by Rubeus Hagrid, guarded a trap door that led into the Chambers. Towards the end of the school term, Professor Quirrell gained access to the trap door by enchanting a harp to play music which lulled Fluffy into a state of sleep.

The Defence Against the Dark Arts Classroom is where Defence Against the Dark Arts class is taught. It is located on the third floor. In 1991, Professor Quirinus Quirrell taught in a different classroom because the third floor was out of bounds. An iron chandelier hung from the ceiling, as well as a Dragon's skeleton. On one end of the classroom stands a projector that is activated by magic. Several desks and tables can be found in the classroom as well as some sets of large windows. The classroom decoration had several changes over the years, spanning from lots of pictures of Gilderoy Lockhart to tons of skeletons and Shrunken Heads.