It was made of brass and was in the shape of a Griffin. It would have been used a great deal of times since its creation, due to the fact that most visitors will have used it as a precursor to entering the Headmaster's/Headmistress's office.
In December 1992, Harry Potter was escorted to the Headmaster's Office for the first time by Minerva McGonagall, after Justin Finch-Fletchley and Nearly Headless Nick had been found mysteriously petrified.
In May 1995, Harry Potter once avoided its use (involuntarily) by standing outside Albus Dumbledore's office, listening to a conversation between Dumbledore, Cornelius Fudge and Bartemius Crouch Junior (who was disguised as Alastor Moody at the time), when Bartemius noticed Harry's presence with Moody's magical eye, thus opening the door for Harry.
On 18 December 1995, Harry Potter, Ron Weasley and Professor McGonagall entered Dumbledore's office, with McGonagall knocking on the door first with this knocker, to alert him of the attack on Arthur Weasley that had just occurred.
Behind the scenes
- Before the release of Harry Potter and the Deathly Hallows, many people assumed that the griffin-shaped knocker was one of Lord Voldemort's Horcruxes. It was known that Voldemort was keen on having one of his seven Horcruxes to represent something from each Hogwarts House. He had chosen Hufflepuff's cup, Slytherin's locket and Ravenclaw's diadem to be Horcruxes so it was thought that the "Griffin Door" (Gryffindor) knocker was made a Horcrux by Voldemort when he applied for a job at Hogwarts.
- Harry Potter and the Chamber of Secrets (First appearance)
- Harry Potter and the Goblet of Fire
- Harry Potter and the Order of the Phoenix
- Harry Potter and the Half-Blood Prince