Monsters in the movies: Harry Potter and the Chamber of Horrors

SNOW WHITE AND THE SEVEN DWARFS (1937)

Supposedly, the Wicked Queen was modelled on Gale Sondergaard - the actress who was also first choice for the Wicked Witch of the West. Her obvious beauty is one of the most disturbing elements in the film: you know you're supposed to be on Snow White's side, but honestly, isn't her stepmother more alluring? For some young boys, her pallid hauteur was an early introduction to the dark side of sexuality, a hint that it might not be all clean and nice between those sheets, and you might not want it to be. And the spell that turns her into a hag, with its screams and lurid bubbles, is one of the great mad-scientist scenes in cinema.

Wicked Witch of the West

THE WIZARD OF OZ (1939)

Film villains had been ugly before, but Margaret Hamilton's green complexion and prosthetic nose inaugurated a new era of extreme physical nastiness. She starts out as Dorothy's dog-hating neighbour Miss Gulch, shrieking and pedalling on her bike through the air after the cyclone hits.

As the hideously ugly witch, she can really let rip, and does, screaming: "I'll get you, my pretty, and your little dog too."

For poor, lost Dorothy, the cackling witch is too much to handle: but in the end, how scared can you be of somebody who melts in water? It's those damn flying monkeys who really add the element of horror.

Cruella de Vil

101 DALMATIONS (1996)

In the live-action version, Glenn Close was menacing in an upmarket, camp and terrifyingly intelligent way as the fearsome inhabitant of Hell Hall. But the grown-ups among us just can't forget the cartoon Cruella - a jagged streak of pure egotism, topped by that inexplicable black and white hair. (In the Dodie Smith book, it was turned that way by drinking a bottle of ink). Her sheer malice is summed up in one terrible fact: she wants to use puppies - puppies! - to make a fur coat and she will trick good, honest dog-lovers without turning a hair. Like so many of the scariest films, this is a nightmare about being orphaned - the fact that these children have white fur with black spots only makes them more lovable, their plight more pathetic. Older girls may come to appreciate that the fashion-mad, road-hogging Cruella is an independent woman living in a man's world.

The Merpeople

HARRY POTTER AND THE GOBLET OF FIRE (2005)

Given the huge choice of terrifying characters - from fire-breathing dragons to You-Know-Who - peopling the latest Harry Potter film, it is surprising that the Merpeople have turned out so - well - scary.

These xenophobic moat dwellers - they live in the waters lapping at the walls of Hogwarts - are apparently scaring the living daylights out of cinema-goers, including, it seems, grown-up film critics.

The consensus seems to be that the Merpeople - depicted in the book with grey skin, green hair, yellow eyes and broken teeth - are the most frightening bit in the new movie. They are shown with mouths open, facing the camera with their ghastly hair swirling around them. Harry encounters them during the Triwizard Tournament, a kind of magical triathlon. In one round, he has to swim to the bottom of the lake to rescue a friend from their chilly clutches.

The scary make-up will no doubt come as a rude awakening for children fed a diet of beautiful mermaids reclining on rocks. In fact, it's totally superficial and the Merpeople actually turn out to be quite friendly; they even put in a good word for Harry with Dumbledore. But not friendly enough to avoid the wrath of the Daily Mail, which yesterday labelled the movie Scary Potter and warned: "In rare cases, children can develop phobias as a result of seeing a film and those can persist into adulthood".

The question arises: can Merpeople be half as scary as a regular diet of Daily Mail stories about asylum-seekers and working mothers?

The Child Catcher

CHITTY CHITTY BANG BANG (1968)

This was the strange man your parents and those public information films they showed at school warned you about - the one who offers you sweets if you'll go along with him...

With his cooing cry of "Ice cream! Chocolate!" and his cage on wheels, the Child Catcher is clearly related to the witch in the gingerbread house in Hansel and Gretel (and his pointed nose marks him out as kin to the Wicked Witch in The Wizard of Oz). But this is a post-Nazi witch: children, for him, are a kind of Untermenschen, for whom he feels a loathing that borders on hysteria. The great dancer Robert Helpmann gave him a spidery grace and took what seems to me now, watching through adult eyes, an almost perverse pleasure in locking children up. His catchphrase was suitably alarming: "There are children here: I can smell them."

Bill Sykes

OLIVER! (1968)

In most versions of Oliver Twist, Fagin is the scary one. But in the musical, Ron Moody's Fagin is far too full of energy and mischief to be unlikeable: it's Oliver Reed's low-voiced, sneering Sykes who makes the running. Reed's pale blue eyes were well-adapted to cruelty; in hindsight, perhaps it was his drinking that gave them that blankness. Every time Oliver thinks he's found a family Sykes finishes the dream off - snatching him away from kind Mr Brownlow, murdering motherly Nancy. His nastiness is proven when he even kills the dog, Bullseye.

The Oogey Boogey Man

THE NIGHTMARE BEFORE CHRISTMAS (1993)

Tim Burton's Halloween fantasy is the most creepy animated film ever made. Most of the ghouls and spooks are, at bottom, decent folks; only the Oogy-boogey man is wedded to unpleasantness and fear. The film has many queasy visual pleasures to offer; but the disintegration of the Oogey Boogey Man into a wodge of bugs and crawling things seems to hint at something genuinely perverse, dredged up from bits of the subconscious that most of us don't have, and certainly don't want to visit.

Voldemort

HARRY POTTER AND THE PHILOSOPHER'S STONE (2001)

Even before The Goblet of Fire, Harry Potter was pushing the envelope on what was acceptable in films that young children might see. Giant serpents and Dementors were disturbing; but they don't match up to the moment in The Philosopher's Stone when Voldemort turns up, snake-eyed and malevolent, on the back of Professor Quirrell's head. How will Ralph Fiennes, seen here as Voldemort in the new movie, beat that?

The Grand High Witch

THE WITCHES (1990)

Witches divide into the glamorous and the repulsive: Anjelica Houston can do both at once. In Nicolas Roeg's version of Dahl's story, in which a small boy stumbles across a witches' convention at a seaside hotel, she has help from some superb prosthetics.

Within the limits her menacing beauty permits, Huston looks quite normal to begin with. Then she unmasks and unwigs, to reveal a bald, scythe-nosed crone. Absolutely terrifying.

Agatha Trunchbull

MATILDA (1996)

Roald Dahl had an acute sense of how irrational adults look to children, and how unfair it seems that their size allows them to dominate. Agatha Trunchbull, the bully of a headmistress in Matilda, embodies this injustice: snaggle-toothed, broken veined, gargantuan (she is a former champion hammer-thrower), her staring eyes have - in Pam Ferris's brilliant performance - a gleam of real insanity. There is no false psychologising here: Miss Trunchbull threatens and hurts children because she can, and because she doesn't like them. The scene in which she hunts Matilda through her house - sniffing like a guard-dog, her huge hams bearing down like thunder as she runs - is utterly paralysing, and brings home the awful truth that children, however brave and resourceful fiction makes them, can never really fight back. Of Roald Dahl's many horrific characters (see the Grand High Witch, above), she is the most believably evil.