Tiffany is a trainee witch whose growth into her job forms one of the many arcs in the Discworld series. She is the main character in The Wee Free Men, A Hat Full of Sky and Wintersmith. According to The Art of Discworld, Terry Pratchett has plans for a fourth novel featuring Tiffany: I Shall Wear Midnight has been given as the possible title. Tiffany is intended to age a number of years between each novel, and not be stuck in her youth, like the Famous Five.
A very young witch (13 at her last appearance), Tiffany hails from the Chalk downland Rimward of the Ramtops. Her grandmother, Sarah Aching, was a shepherd, and by Ramtop standards was also a witch, although witchcraft was frowned upon on the Chalk, until Tiffany's arrival. Granny Aching was a friend of the Chalk Clan of Nac Mac Feegle, (an army of tiny, blue, rowdy, drunken and vaguely Scottish ne'er-do-wells) and they have befriended Tiffany as the new "hag o' the hills". As Tiffany was their Kelda (Queen) for a short time, the Nac Mac Feegle see her as their responsibility, and there is no time in Tiffany's life since then when they have not (in)discreetly watched her.
Tiffany began her witching career at nine, upon being scouted by the "witch finder" Miss Tick. She led the Feegles on a journey into Fairyland to rescue Wentworth, her sticky toddler brother, and Roland, the young son of the local Baron, from the Queen of the Elves. For this she earned the respect of Granny Weatherwax, a not insignificant achievement in itself. Although at the time she was too young to be a witch, Granny gave her an imaginary invisible hat to boost her confidence. Such is the power of belief on the Disc that it was actually capable of keeping off the rain. Two years later she travelled to Lancre to be formally apprenticed to the witch Miss Level, and later to Miss Pullunder and Miss Treason. After Miss Treason's death, she was briefly apprenticed to Nanny Ogg before returning to the Chalk and assuming her anointed position as the Witch of the Chalkland.
Like Granny Weatherwax, Tiffany has prodigiously mastered the art of Borrowing (stepping outside one's self), though she didn't recognise it at the time. This left her body vulnerable to infestation by a "hiver" (a gestalt entity of minds from the dawn of time) that used her power to harm and cause chaos. She eventually managed to overcome the hiver by giving it what it truly wanted: the ability to die. She's also very good at making cheese; indeed she has managed to create one particular blue cheese, named Horace, which has the peculiar habit of eating mice. She has read the entire dictionary, although she sometimes has difficulty with pronunciation. Tiffany also has an innate talent with languages - a side effect of the brief possession by the hiver. The occupation of her mind by the creature that collected minds has left her with shadows of those memories, including a deceased, didactic wizard named Sensibility Bustle, who translates any foreign word inside her head upon hearing or seeing it.
While training in Lancre, she attended a "coven" of young witches "led" by Annagramma Hawkin ("led" basically meaning she had the sharpest voice and was bossy). Tiffany and fellow coven members Lucy Warbeck and Petulia Gristle eventually acquitted themselves well as witches; Annagramma, however, found that her training, under the tutelage of the arrogant and superficial Letice Earwig, had not been nearly enough to prepare her for the reality of witching life, and her onetime coven subordinates agreed to help her get on her feet.
Recently, Roland has indicated strongly that his affection for Tiffany may extend far beyond mere gratitude, as evidenced by his willingness to play the role of the mythic Hero in the attempt to rescue Tiffany from the romantic attentions of the wintersmith and undo the damage she caused by interfering with the Dance of the Seasons. Tiffany was at first ambivalent towards the wintersmith, unnerved by the attention, but also somewhat flattered that she had caught the eye of a godlike being. The wintersmith continued its advances, even attempting to create a human body out of snow and miscellaneous elements, according to a child's song. Tiffany, after some advice from Nanny Ogg about the power a young woman has over a suitor, managed to control the wintersmith for a time, however, eventually he gained the upper hand and brought a record-breaking snow and cold to the Chalk in what should have been early spring, threatening the new lambs. She later melted him using a trick taught by Granny Weatherwax, fulfilling her temporary role as the Summer Lady and allowing the real one, brought from the Underworld by Roland, to resume her role. Tiffany herself denies having any affection for Roland, but there are many signs that she does have feelings for him, even though she will not admit it. The story progresses in I shall wear midnight, with a new love interest called Preston who is a guard for the baron and with an intellect similar to Tiffany's. In the disc version of The Wee Free Men, Tiffany and other people living on the chalk speeak with a Geordie accent.