“Well, the Heads of the participating schools are always on the panel ...because all three of them were injured during the Tournament of 1792, when a cockatrice the champions were supposed to be catching went on the rampage. ... It’s all in Hogwarts, A History."
-- Hermione Granger (GF15)
A Cockatrice is a combination of a rooster and a dragon or snake.
- A cockatrice went on a rampage in the Triwizard Tournament of 1792 (GF15).
The legendary creature called the cockatrice is actually almost a twin of the basilisk. Some of the characteristics of the basilisk in the Potter books are actually those of the cockatrice, such as the ability to turn people into stone with a glance. Some medieval bestiaries say that the weasel is the only animal which is immune to its petrifying stare. (The Lexicon page 64).
This is a creature which Rowling did not invent.
There is a 1974 children's fantasy book by British writer Gerald Durrell called The Talking Parcel or the Battle for Castle Cockatrice. It was made into a TV show in 1978. The book also features werewolves, a phoenix, a mooncalf, and a sea serpent.
From the Web
"Cockatrice" from Harry Potter Wiki