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. There, he was a close friend of Sirius Black, James Potter and Remus Lupin, although he was the least intelligent and least talented of the gang. With Sirius and James' help, Pettigrew became an Animagus, with the ability to transform at will into a rat. After leaving Hogwarts, Pettigrew joined 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 to 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 sought revenge on Pettigrew but, during the confrontation, Pettigrew publicly accused Sirius of the Potters' deaths, murdered twelve nearby Muggles, and then cut off his own index finger before transforming 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. Wanting to keep an eye on the wizarding world, he masquerades as a rat, first as Percy Weasley's pet, and then as Ron Weasley's. They named him Scabbers.

Although Pettigrew appears in the first two books in the form of Scabbers, his identity was not revealed until Prisoner of Azkaban where he served as the main antagonist of the novel. When a photograph of the Weasley family appears in the Daily Prophet newspaper, Sirius recognised him, prompting Black's escape from Azkaban. The two eventually confronted each other in the Shrieking Shack, where Lupin and Black forced "Scabbers" to resume his human form. Pettigrew confessed his treachery, claiming to have committed it only to save his own life. With Sirius and Lupin 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' innocence. But Pettigrew managed to escape while being led out of the Shack when Lupin begins to transform into a werewolf. Harry's actions, however, resulted in Pettigrew owing him a life debt.

Pettigrew then returned to the service of Voldemort, seeking him out in the forests of Albania and helping him to return to a feeble baby's body. He also abducted a Ministry of Magic employee named Bertha Jorkins, who was able to provide Voldemort with valuable information. Pettigrew (almost always referred to as "Wormtail" hereafter) assisted 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, Wormtail murdered 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 replaced Wormtail's severed hand with a silver hand that possessed five intact fingers and great strength. Despite his lead role in the return of Voldemort, Wormtail's fortunes remained 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, Wormtail checks on the prisoners and is unsuccessfully attacked. Wormtail 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.