From rats to cats, taking Animagi from page to screen was always going to be a challenging business. Here’s how, combining live animals and animatronics, the effect was achieved...

Peter Pettigrew transforms back into a rat and escapes.
Harry Potter and the Prisoner of Azkaban

Extracted from Harry Potter: The Creature Vault by Jody Revenson
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In the world of Harry Potter, an Animagus is a witch or wizard who can choose at will to turn him or herself into an animal. There are some instances where the Animagus form of a wizard may display a recognisable mark, physical or nonphysical, that can identify them, and that the Patronus of an Animagus are often the same animal species.

Animagus example 1

MINERVA McGONAGALL

The Animagus form of Professor Minerva McGonagall is a grey tabby cat. This feline form of the professor allows her to covertly observe Harry Potter’s relatives, the Dursleys, in Harry Potter and the Philosopher’s Stone. McGonagall also uses her Animagus form to monitor her first-year’s Transfiguration class.

Professor McGonagall’s Animagus form was played by a tabby cat named Mrs. P. Head. No additional makeup or computer effects were needed, as the cat already had the required ‘spectacle’ markings. When Harry and Ron Weasley enter her Transfiguration class in the film version of Philosopher’s Stone, McGonagall’s Animagus form leaps from her desk and morphs into the human McGonagall. For this action, a trainer underneath the desk held the end of an invisible safety harness that was settled on the accomplished animal actor. Sitting directly above the trainer, Mrs. P. was given a cue to spring off the desk, and the safety harness was released at the same time. This film segment was then composited with a computer-generated transition from feline to professor.

McGonagall clutching a scroll
Harry Potter and the Philosopher’s Stone

Animagus example 2

SIRIUS BLACK

Sirius Black’s Animagus form is that of a large black dog his friends call Padfoot, first seen in Harry Potter and the Prisoner of Azkaban. Sirius, James Potter, and Peter Pettigrew studied to become Animagi when they discovered that fellow Gryffindor Remus Lupin was a werewolf. Sirius and James, who turned into a stag called ‘Prongs’, were able to control Remus during his monthly transformations. Sirius takes advantage of his Animagus form in Harry Potter and the Order of the Phoenix to stealthily see Harry Potter off to Hogwarts.

In Harry Potter and the Prisoner of Azkaban, Padfoot, who is initially mistaken for the Grim, was a computer-generated Animagus. The filmmakers brought in a show dog named Fern (full name: Champion Kilbourne Darling), a Kilbourne deerhound, as reference for the part. Fern was fitted with pointed ears and learned to jump ramps to perform the stunts needed for the character’s digital template. Fern was backed up by another Kilbourne deerhound named Cleod. An award-winning show dog (full name: Champion Kilbourne MacLeod), Cleod’s normally grey fur was darkened with a temporary rinsible black dye. Sirius’s Animagus form was recast for his appearance in Harry Potter and the Order of the Phoenix. This time he was played by a Scottish deerhound named Quinn, who was a rescue dog. Quinn’s trainer describes him as being a little stubborn, but with a fun-loving nature.

Sirius Black pointing his finger in the Shrieking Shack
Harry Potter and the Prisoner of Azkaban

Animagus example 3

PETER PETTIGREW

During the events of Harry Potter and the Prisoner of Azkaban, Harry Potter learns that his father, James, was close friends with Sirius Black, Remus Lupin, and Peter Pettigrew, who attended Hogwarts together. Pettigrew became an Animagi, along with James and Sirius, transforming into a rat they called ‘Wormtail’. When Pettigrew betrays James and Lily Potter to Voldemort, he goes into hiding as the Weasleys’ family pet, Scabbers.

The Animagus form of Peter Pettigrew in Harry Potter and the Prisoner of Azkaban was played mainly by a rat named Dex, in addition to several animatronic rat versions. For the transformation from the rat to Peter Pettigrew in the Shrieking Shack, a combination of real and animatronic rats were used. When Sirius Black first reveals that the rat Ron Weasley is holding is not Scabbers but Pettigrew in his Animagus form, actor Rupert Grint (Ron) is holding Dex, but it is an animatronic version of Wormtail that is snatched out of his hands by Gary Oldman (Sirius).

From rat to Wormtail the progression of Pettigrew
Harry Potter and the Prisoner of Azkaban

Dex was trained to run from a point A to a point B, an example being when – in an effort to escape – Wormtail runs over the piano and across the floor in the Shrieking Shack. Any other occasion where the animal would drop, be thrown, grabbed, etc., would be enacted by an animatronic or digital version.

Unlike Professor McGonagall and Sirius Black, Peter Pettigrew exhibits obvious rat-like features in his human form. The makeup team matched the colour of the rat’s fur to the wigs created for Timothy Spall, the actor who played the human version of Peter Pettigrew, and gave him rat-like teeth and nails.

Harry Potter and the Prisoner of Azkaban

Harry Potter: The Creature Vault book cover