Something huge hit the stone floor of the chamber, Harry felt it shudder. He knew what was happening, he could sense it, could almost see the giant serpent uncoiling itself from Slytherin’s mouth. Then he heard Riddle’s hissing voice: ‘Kill him.’

The Basilisk was moving towards Harry, he could hear its heavy body slithering ponderously across the dusty floor. Eyes still tightly shut, Harry began to run blindly sideways, his hands outstretched, feeling his way. Riddle was laughing …
-J.K. Rowling, Harry Potter and the Chamber of Secrets

The Basilisk in The Chamber of Secrets harkens back to the very first attested idea of a Basilisk — that of a large, extremely venomous serpent with a deadly stare — featured in Plinius the Elder’s Naturalis Historia. Unlike Plinius’s Basilisk, however, Rowling’s is gigantic in size. In the novel, it is described as an “enormous serpent, bright, poisonous green, thick as an oak trunk,” with “deep yellow eyes” and “fangs long and thin as sabres.”

The Basilisk in the film version was established as being 80 feet in length. Robert Bliss designed the beast, with real-life reference provided by an eight-foot long Burmese Python named Doris. Initial iterations maintained a relatively simple snake-like appearance, but the concepts progressively began implementing subtle characteristics of other reptiles — such as monitor lizards and crocodiles — resulting in the Basilisk taking on a more dragon-like appearance. The textures were based on snakes, but made “a little more exaggerated than say, a normal snake’s,” according to Chris Fitzgerald, part of the sculpting crew. The Basilisk’s skin was endowed with osteoderms and other hard scales, and unlike real snakes, the creature was given functional eyelids — closer to a lizard or a bird than a snake.

“Of the many fearsome beasts and monsters that roam our land, there is none more curious or more deadly that the Basilisk, known also as the King of Serpents. This snake, which may reach gigantic size, and live many hundreds of years, is born from a chicken’s egg, hatched beneath a toad. Its methods of killing are more wonderous, for aside from its deadly and venomous fangs, the Basilisk has a murderous stare, and all who are fixed with the beam of its eye shall suffer instant death.”

A small-scale maquette was sculpted by Robert Bliss and Chris Fitzgerald to be scanned digitally. The original intention was to bring the Basilisk to the screen as a fully digital creation; only the shed skin of the Basilisk was to be built practically. Given that a full sculpture was needed to eventually mould the shed skin out of it, Dudman suggested to build a practical insert puppet of the Basilisk. The choice was sound on two fronts — not only would it lessen the amount of needed digital effects sequences (thus save budget), but it would also provide the young Daniel Radcliffe with a physical monster to react to.

Following the new direction, Dudman’s crew needed to sculpt the Basilisk’s head and neck. Gary Pollard led the creation of the full-size sculpture. The interior of the monster’s mouth was sculpted and moulded separately from the rest of the body to increase its sculptural detail and ease the casting process. The sculpture was moulded to obtain both the skins for the full-size puppets as well as the shed skin found early on in the Chamber scenes. The shed skin was cast in urethane rubber for a translucent effect, with fiberglass inserts to enhance its organic quality.

The main Basilisk puppet was an animatronic, mechanized by Phil Ashton and Malcolm Evans. Its eyes were already gouged out, as the shots of the Basilisk before Fawkes’s attack were all planned to be digital. This also saved the crew the effort of having to develop functional eyes. The puppet, like Aragog, employed aquatronics instead of traditional hydraulics — allowing for smoother gross movements. The Basilisk animatronic had a fluid range of head and neck movement. The head was fully operational, with a jaw-opening mechanism, as well as moving eyelids, nostrils, and tongue. The fangs of the creature were cable-controlled and could retract as its mouth closed and move forward as it opened — a trait inspired by real snakes.

The internal structure of the puppet was custom-devised with aluminium ladders: “when we looked at the design of the snake,” Dudman told Cinefex, “we knew we needed to build sort of a geodesic structure for its body. When I looked at the drawing for that structure on the computer, I said, ‘it looks like step ladders to me.’ I knew it would save us a huge amount of machining if we just used step ladders for the bulk of the structure, so that’s what we did.” This step-ladder framework housed the internal mechanisms and was thus reinforced to sustain more weight. It was covered with a tubular armature — also built in aluminium to ensure both light weight and endurance — over which the Basilisk’s skin was laid. The foam latex skin was painted by Astrig Akseralian (the lead painter, and painting supervisor of the Basilisk models), Elaine Cartwright Best, and Mel Lenihan.

The Basilisk was mounted on the same rig the team had built for Aragog — a pole-armed teeterboard with a counterweight on the other end. The creature could be raised and lowered, and also mounted on tracks or on a ram depending on the requirements of the shot. The snake could slither up on its track to get close to Radcliffe for the fighting scenes. “It was a big rig, and it moved incredibly well,” Dudman said. “They used it ten times more than they ever thought they would.”

The practical Basilisk was intercut with a fully digital version of the monster, featured in the majority of the effects scenes. The total of 45 visual effects sequences were devised by Framestore. The digital model of the Basilisk was first obtained from a scan of the small-scale Basilisk maquette, which was then refined manually to match the appearance of the animatronic. For rendering and animation, the digital effects artists used Maya, Houdini and Renderman. The textures were painted by Jason Horley in Photoshop.

The Basilisk animation referenced snakes, lizards and crocodiles. Animation supervisor Michael Eames explained: “we had to see the snake in close-ups, and in those shots, we had to lead the animation from the head. We also had to have it appear in long shots where it was dragging on the ground.”

Character rigger Felix Balbas devised a set-up that allowed the animators to switch from inverse kinematics to spline weighting or forward kinematics, depending on the requirements of a specific animation sequence. Eames continues: “for example, when the snake is chasing Harry, its head is down low and its body is working along a path: then as it comes up to Harry, its head is up and its body starts to slow down. Obviously, some of the body is still rigidly in contact with the ground. So we had a range of controls that faded off their range of ingluence from the neck into the body to control body parts independently.” Crucial to the animation was also the Basilisk’s interaction with water, which was achieved with digital water elements (including flow maps for the water that dripped off the creature’s skin) as well as practical water elements composited into the shots.

Harry stabs the Basilisk through the roof of its mouth (a composite shot with the digital Basilisk), fatally wounding it. In a Harryhausen-like animation sequence, the Basilisk flails about in its death throes, then ultimately falls after pointing its head towards Slytherin’s visage one last time.

After the Basilisk’s death, its corpse is seen lying on the floor of the Chamber. For this purpose, a second practical version of the Basilisk was built — plain dummy, painted by Elaine Cartwright Best and other painters. The skin was moulded in foam latex and polyurethane. Dudman related: “when it got wet, it turned into a sponge, which made it nearly immovable, and it began to rot. We had to drag it out and spray it with disinfectant.”

The Basilisk’s skeleton makes a cameo in Harry Potter and the Deathly Hallows: Part II for which the Chamber of Secrets set was recreated using both digital and practical elements. The corpse was an eight-foot long full-size model of the Basilisk’s skull and neck vertebrae, sculpted by a team of sculptors led by Shaune Harrison and then moulded in fiberglass.

For more pictures of the Basilisk, visit the Monster Galleries:

• Harry Potter and the Chamber of Secrets
• Harry Potter and the Deathly Hallows: Part II