Augustus Rookwood

Algernon Rookwood was a spy at the Department of Mysteries in the Ministry of Magic who worked for Lord Voldemort during the First Wizarding War. After he was named by his comrade Igor Karkaroff, Rookwood was arrested and imprisoned in Azkaban. He was freed during the 1996 mass break-out and served as a Death Eater once more. During the final battle of the Second Wizarding War, Rookwood was defeated by Aberforth Dumbledore, and is currently presumed to be incarcerated once more.

Years as a Spy
Rookwood worked as an Unspeakable in the Department of Mysteries, but became a Death Eater and spy for Lord Voldemort during the First Wizarding War. He had an information network inside and outside of the Ministry of Magic with a number of well-connected wizards. Whether or not these wizards knew they were being used for information by Rookwood is unknown. What is known is that Ludovic Bagman gave Rookwood information, likely ignorant of the fact of Rookwood's real affiliations, since Rookwood dangled the prospect of a Ministry position before Bagman. Bagman's testimony revealed that Augustus Rookwood was friends with his father. He also referred to Rookwood rather affectionately as "Old Rookwood", despite the man being a Death Eater, during his own court case.

From that information, it can be deduced that Rookwood was outgoing and perhaps affable during his years as a spy, breaking the mold of so many other Death Eaters.

Conviction, Incarceration, and Breakout
In 1981 or 1982, Rookwood was captured and convicted on testimony from Igor Karkaroff as to his Death Eater activities and imprisoned in Azkaban. This was one of many names that Karkaroff surrendered in order to achieve his own freedom. Rookwood escaped Azkaban along with nine other Death Eaters in 1996 when the Dementors defected to the recently-returned Lord Voldemort.

Involvement in the Break-In of the Department of Mysteries
Rookwood was responsible for getting Voldemort on track with stealing the prophecy which concerned the Dark Lord and Harry Potter, who saw Rookwood in one of his dreams. Obviously, his experience in the Department of Mysteries made him invaluable in this function.

After numerous attempts at stealing the prophecy failed, Voldemort lured Harry to the Ministry by sending him visions of his godfather being tortured there. Rookwood was one of twelve Death Eaters who participated in the ambush of Harry and his five friends, and in the battle which ensued when the teenagers resisted. He was the only one not assigned a partner as the Death Eaters pursued the six D.A. members. Rookwood's whereabouts for most of the battle were unknown. There are a few theories on this, ranging from Rookwood stealing Department of Mysteries items to Rookwood using the department's items against Dumbledore's Army and actually manipulating time.

What is known is that Rookwood was apparently uninjured when he entered the Veil Room, and was seen casting the Killing Curse at Kingsley Shacklebolt without his mask on. It is presumed that Rookwood, along with all the other Death Eaters aside from Bellatrix Lestrange, was captured and imprisoned in Azkaban after the battle.

However, he was again at large the following year, after another Azkaban break-out.

Battle of Hogwarts
"ROOKWOOD!"

- He (Percy) let out a bull-like roar and set off in the direction of a tall man, who was chasing a group of students.

During the Battle of Hogwarts in 1998, Rookwood fired a curse that damaged a great deal of the castle and was believed to have killed Fred Weasley. Percy Weasley eventually found and went after him as he was attacking some of the students who refused to evacuate the school, instead staying to fight Voldemort and his army. Later in the battle, he was stunned by Aberforth Dumbledore.

It is presumed that after Voldemort's final defeat, Rookwood was either killed or re-imprisoned.

Physical appearance
Rookwood is described, judging by his mugshot seen in the Daily Prophet, as a pock-marked and greasy-haired man who seems to have been bored, contrasting from the majority of the other Death Eaters in the mugshots, who were sneering and glaring.

Etymology
"No mate ever brook would a Rook of the Rookwood!"
 * Rookwood was named as Algernon Rookwood in Harry Potter and the Order of Pheonix, but his name reverted to Augustus again later on.
 * Augustus is Latin for "majestic" or "venerable", derived from the Latin augere, "to increase". It was the title given to the first emperor of Rome and subsequently to make other Roman emperors.
 * Rooks are known to be extremely sociable birds, and also have a kind of caw that sounds like a croak. Rookwood is indicated to be a sociable wizard, and when he was seen speaking to Voldemort, he was hoarse and his tone was described as a croak.
 * The surname "Rookwood" may also come from Ambrose Rookwood, one of the conspirators in the Gunpowder Plot of 1605.
 * Rookwood is also a family in the 1834 romance of the same name written by William Harrison Ainsworth. In the novel, the Rookwood family are described quite negatively:

- A merry saying it is, and true. No woman ever stood in a Rookwood's way but she was speedily removed—that's certain. Other possible references from Rookwood are the surname Turpin (Lisa Turpin), from the famous highwayman, and the Hand of Glory that is the subject of a poem within the book.