The most frightening is probably Lucy Lane Clifford's The New Mother, a fable in which a brother and sister are incited to naughtiness by a strange girl they meet after the fair has been in town. Their mother threatens that if the naughtiness continues, she will go away and they will get a new mother "with glass eyes and a wooden tail". This comes from Anyhow Stories, Moral and Otherwise (Macmillan, 1882) which included The New Mother. Other Lucy Lane Clifford works were, for their time, considerably groundbreaking, such Mrs Keith's Crime, which concerns an ailing young widow who makes the considered decision to kill her also-consumptive daughter; and Aunt Anne, the story of a woman of 68 who marries a man of 27.
The background is interesting: a novelist and journalist, Clifford was half of a highly intellectual partnership as the wife of the philosopher and mathematician William Kingdon Clifford (see Such Silver Currents: the Story of William and Lucy Clifford 1845-1929, Monty Chisholm, Lutterworth Press, 2002, ISBN-13: 9780718830175). Charlotte Moore, writing in the Guardian (Mind the gap, Wednesday May 22 2002) reads another Clifford story, Wooden Tony, as a description of autism, suspecting it to be based on first-hand knowledge. From outside the world, the story of a girl who doesn't relate to human concerns, could also be interpreted in that light. However, Moore's implication that WK Clifford was autistic
She was "the wife of the philosopher and mathematician WK Clifford"; that phrase rings a warning bell"
doesn't especially wash. According to the ODNB, despite his mathematical genius he was an entertaining public speaker and a sociable and popular guy:
Clifford's friends described him as having an amicable attitude towards everyone but enjoying himself most when planning children's parties and joining in the entertainment.
- Albert C. Lewis, "Clifford, William Kingdon (1845–1879)", Oxford Dictionary of National Biography, Oxford University Press, Sept 2004; online edn, May 2006, accessed 7 Sept 2008
There's more about him and Lucy in the paper William Kingdon Clifford (1845–1879) and his wife Lucy (1846–1929) (PDF) by the abovementioned Monty Chisholm.
The second story I like is Harry's rash wish, and how the fairies granted it (The Hon. Mrs Greene, Frederick Warne and Co, 1891). This concerns a boy called Harry Thompson who is irritated by his baby sister and says, "I hate babies! I wish there were no such things in the world!". The next day he wakes and finds himself in a deserted landscape, where he eventually finds a single surviving man, 115 years old, who recalls how a century earlier someone's wish had caused no more babies to be born. Despite the twee mechanism of the wish, the story has a borderline-SF flavour (Greybeard by Brian Aldiss and The Children of Men by PD James naturally spring to mind). It can be found online here at the State University System of Florida libraries Literature for Children, or here at the Baldwin Library of Historical Children's Literature, George A. Smathers Libraries, University of Florida (both excellent archives of this genre). The author, the Honourable Mrs Louisa Lilias (aka Lelias) Greene (1833-1886), was a minor Irish aristocrat, a daughter of one of the Baron Plunkets. Her works - see the Cambridge Bibliography of English Literature at Google Books - are largely forgotten.
A third story on the dangers of naughtiness and incautious wishing is Edith Nesbit's 1899 Whereyouwanttogoto or The Bouncible Ball. The author and political activist Edith Nesbit is best known for her children's classics, notably The Railway Children, Five Children and It and The Phoenix and the Carpet. Her stories didn't, however, exclusively target a child readership; Five Children and It (as a series of stories) and The Seven Dragons and Other Stories (from which Whereyouwanttogoto comes) were originally published in the Strand Magazine.
Whereyouwanttogoto concerns Selim and Thomasina, two bored siblings stuck with uptight relatives in London, who are transported by a sentient rubber ball to an idyllic magical seaside where they can play as they like, go to bed as late as they wish, and every meal is unsupervised and delicious. Yet this paradise proves a tenuous reality, which is instantly reshaped by wishes based in dissatisfaction.
The next day they got out as early as they could and played water football with the seal and the Bouncible Ball, and when dinnertime came it was lobster and ices. But Thomasina was in a bad temper. She said, "I wish it was duck." And before the words had left her lips it was cold mutton and ricepudding, and they had to sit up to table and eat it properly too, and the housemaid came round to see that they didn't leave any bits on the edges of their plates, or talk with their mouths full.
This idea has been revisited many times in later fiction; it reminds me of the Star Trek Old Series episode Shore Leave; or the Red Dwarf episode Better Than Life, in which Rimmer's negative thoughts sabotage a virtual reality paradise; or even the "monsters from the id" that destroyed the Krell in Forbidden Planet - a motif that Colin Wilson paid homage to in his novel The Philosopher's Stone, where much the same happens to his Lovecraftian Old Ones:
"They had overlooked one absurd point. As the conscious mind learnt to project its visions of reason and order, the vast energies of the subconscious writhed in their prison, and projected visions of chaos"
Addendum: Victorian Fantasy (Stephen Prickett, Baylor University Press, 2005, ISBN 1932792309) looks an interesting analysis of this subject ("Far from being just children's literature, Victorian fantasy is an art form that flourished in opposition to the repressive social and intellectual conditions of Victorianism"). Prickett, for instance, contrasts the approaches of Lucy Clifford and Edith Nesbit. He argues that the former exemplifies an approach of threatening children with irrational horrors (The New Mother, ostensibly a Christian moral tale about obedience, has far older archetypal deeps); while the latter sought to exorcise such horrors. Nesbit's stories feature supernatural creatures, but they are generally non-threatening when the children in the stories interact with them rationally. A deal of Victorian Fantasy is previewable via Google Books.