This article refers to the organization in the Harry Potter novels. For the Greek honour and medal by the same name, see Order of the Phoenix (Greek medal).
The Order of the Phoenix is also a fictional organization in the Harry Potter series of books by J. K. Rowling. It is also frequently used to refer to the fifth book in the Harry Potter series, properly known as Harry Potter and the Order of the Phoenix.
What is it?
The Order of the Phoenix is an anti-Voldemort organization established by Albus Dumbledore at the height of Lord Voldemort's powers. Its scope of action extends from covert information gathering to outright battle. Among the original members were Lily and James Potter (Harry's parents), Remus Lupin, Sirius Black and Alastor Moody. The situation of the time put the Order in a vastly disadvantageous position and its casualty rate was around 50%. As Voldemort fell from power after trying to kill Harry, the Order disbanded.
Upon Voldemort's return in Harry Potter and the Goblet of Fire, Dumbledore re-established the Order. It set up headquarters in Number Twelve, Grimmauld Place, London - Sirius' family home. Dumbledore is the Secret-Keeper for this house; as such, it cannot be found by anyone who he has not personally told the location to.
The word phoenix is probably related to Fawkes, Dumbledore's pet phoenix, whose feathers form the core of both Voldemort and Harry's wands. In the fifth book, Dumbledore sends Fawkes on several missions for the Order.
Part of the motivation for restarting the Order was because Cornelius Fudge, Minister of Magic at the time, absolutely refused to believe that Lord Voldemort had risen again. As Fudge insisted that Dumbledore was spreading rumours to try to take him down, the Order went underground - not that it would have kept a high profile at the best of times. When Lord Voldemort was sighted in the Ministry headquarters itself, Fudge was forced to admit that Dumbledore was telling the truth. The gloves are expected to come off.
It is thought that the members of the Order will remain the central characters in the fight against Voldemort, acting as "good" counterparts to Voldemort's Death Eaters.
Members of the original Order of the Phoenix
Known members of the reconstituted Order of the Phoenix