Isabella Thorpe from Northanger Abbey by Jane Austen
She worms her way into the Morlands' affections, becoming confidante to Catherine and dazzling her brother James into a proposal, but all the time she's only after the money she thinks she'll be able to get out of them. A false friend is so much worse than a sworn enemy!
Matilda from Cautionary Tales for Children by Hilaire Belloc
Another one of my mother's favourites, which she bought me as soon as I was old enough to enjoy it, was this volume of poetry by Hilaire Belloc, in which we are told stories of wilful children who meet a nasty end (perhaps my mother was trying to tell me something!). Matilda is one of his most famous creations; an unfortunate child who habitually told lies and was burned to a crisp in a fire. If you've never read Belloc's verses, pop over to Project Gutenberg where you can download them for free - they're not very long and they show British black humour at its very best.
Scarlett O'Hara from Gone with the Wind by Margaret Mitchell
A controversial choice for some, but no matter how much you may admire Scarlett, you have to admit there are times when she deserves a good slap. She goes after Ashley with no regard at all for poor Melly, and she treats Rhett appalingly most of the time.
Chris Hargensen from Carrie by Stephen King
The worst of the bullies who taunt Carrie is Chris Hargensen, who famously pours a bucket of pig blood over Carrie's head at the prom. Fortunately she gets her comuppance by the end of the book.
Hilly from The Help by Kathryn Stockett
She's spiteful and controlling, and wants the whole town to look up to her as its number 1 grande dame. Hilly is a wonderful character who the reader will just love to hate.
Amy March from Little Women
A hateful child, whose worst moment of spite was when she threw her sister Jo's manuscript on the fire. Luckily, she improved as she got older.
Beatrice Lacey from Wideacre by Philippa Gregory
There's absolutely nothing this girl won't do to get her hands on her beloved Wideacre land. She plots to murder her father, sets a vicious trap for her lover, captivates her brother and drives her husband into an asylum. Pure OTT nastiness!
The Ugly Sisters from Cinderella
The original mean girls!
Estella from Great Expectations by Charles Dickens
It's difficult to understand what Pip could possibly see in Estella, who is a cruel and vain young girl who teases Pip mercilessly and taunts him for his common upbriging.