Peter Pettigrew

Peter Pettigrew, nicknamed Wormtail, is the only Death Eater known to have been in a House other than Slytherin (Gryffindor) while at Hogwarts. After leaving Hogwarts, Pettigrew joins forces with Voldemort, and in exchange for his own life becomes Voldemort's spy within the Order of the Phoenix, of which Pettigrew is a member. When the Potters know that their son Harry is Voldemort's target, Sirius suggests them to use Pettigrew as Secret-Keeper because he does not believe Voldemort would ever suspect a “weak, talentless thing” like Pettigrew. Pettigrew betrays the secret to Voldemort, an act that ultimately leads to James and Lily's death. Sirius decided to get revenge on Pettigrew but, during the confrontation, Pettigrew publicly accuses Sirius of the Potters' deaths, kills twelve Muggles, and then cut off his own index finger before turning into a rat, thereby framing Sirius for the betrayal of the Potters, as well as of his own murder and that of the bystanders. Pettigrew is "posthumously" awarded the Order of Merlin, and hides during the next twelve years, masquerading as Scabbers, a pet rat in the Weasley family.

Although Pettigrew appears in the first two books in the form of Scabbers, his identity is not revealed until Prisoner of Azkaban. When a photograph of the Weasley family appears in the Daily Prophet, Sirius recognizes him, prompting Sirius's escape from Azkaban. The two eventually confront each other in the Shrieking Shack, where Lupin and Sirius force Pettigrew to resume his human form. Pettigrew confesses his treachery, claiming to have committed it only to save his own life. When Sirius and Lupin are about to take their revenge, Harry intervenes and begs Sirius to turn Pettigrew over to the Ministry of Magic instead, by which device to prove Sirius's innocence. Pettigrew manages to escape as he is being led out of the Shack when Lupin begins to transform into a werewolf. Harry's actions, however, result in Pettigrew owing him a life-debt.

Pettigrew then returns to the service of Voldemort, and helps keep him alive prior to his return to full corporeal form, and assists Barty Crouch Jr in overpowering Mad-Eye Moody, setting up the events in the fourth book, Harry Potter and the Goblet of Fire. In the climactic confrontation in that book, Pettigrew kills Cedric Diggory on Voldemort's orders, and performs the complex spell to regenerate Voldemort, severing his hand in the process as a sacrifice. Upon his return to full corporeal form, Voldemort replaces Pettigrew's severed hand with a silver hand that possessed five intact fingers. Despite his role in the return of Voldemort, Pettigrew's fortunes remain low; in Harry Potter and the Half-Blood Prince Snape treats him as a servant, and in Harry Potter and the Deathly Hallows he is tasked with keeping watch over prisoners in the cellar of Malfoy Manor. While Harry and Ron are being kept there, Pettigrew checks on the prisoners and is unsuccessfully attacked. Pettigrew begins to strangle Harry with the silver hand, but when reminded by Harry that the latter once saved his life, he hesitates for a moment to think of the life-debt. During the moment of hesitation, the silver hand turns against him and strangles him to death in retribution for his pity.

Pettigrew is portrayed by Timothy Spall as an adult, and by Charles Hughes as a teenager in the films.