Augustus Rookwood is a minor antagonist in the Harry Potter series. He is a Death Eater and a former agent of the Department of Mysteries. He was portrayed by Richard Trinder in the films.
Harry Potter and the Goblet of Fire
Although Rookwood does not appear in this story, he is mentioned in Igor Kakarov's hearing when Karkarov gives his name as a spy for Lord Voldemort, resulting in Barty Crouch Sr. ordering his arrest off-page. He is also mentioned in Ludo Bagman's trial for spying when Bagman states that Rookwood tricked him into passing him secrets.
Harry Potter and the Order of the Phoenix
After the Dementors defect from Azkaban, Rookwood, Bellatrix Lestrange and several other Death Eaters escape, and rejoin the newly reformed Death Eaters. Rookwood is responsible for placing the Imperius Curse on Department of Mysteries worker Boderick Bode to have him break into the Department so he can steal a prophecy concerning Voldemort. Bode fails at this, and is assassinated by the Death Eaters shortly thereafter. Rookwood is accused of being responsible for the failure by Voldemort, but he blames Avery as it was his plan, resulting in Voldemort sending him to find Avery and bring him in for punishment. Rookwood is also present at the Battle of the Department of Mysteries, during which Order of the Phoenix member Kingsley Shacklebolt engages him in a duel and defeats him, resulting in his arrest when Minister for Magic Cornelius Fudge arrives with a team of Aurors, although he escapes again shortly afterwards due the Dementors defection.
Harry Potter and the Deathly Hallows
Rookwood appears during the battle of Hogwarts, during which Ministry employee Percy Weasley sees him attacking a group of students and chases after him. Rookwood is later stunned by Aberforth Dumbledore while trying to enter the Great Hall. What happens to him afterwards is unknown, but he was likely arrested and sent back to Azkaban.