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.
Tiffany begins her witching career at nine, upon being scouted by the "witch finder" Miss Tick. She leads 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 Fairies. For this she earns the respect of Granny Weatherwax, a not insignificant achievement in itself. Although at the time she is too young to be a witch, Granny gives her an imaginary invisible hat to boost her confidence. Such is the power of belief on the Disc that it is actually capable of keeping off the rain. Two years later she travels to Lancre to be formally apprenticed to the witch Miss Level. During her time with Miss Level, her body becomes vulnerable to infestation by a "hiver" (a gestalt entity of minds from the dawn of time) that uses her power to harm and cause chaos. She eventually manages to overcome the hiver by giving it what it truly wants: the ability to die.
At the age of thirteen, while studying under Miss Treason, Tiffany accidentally attracts the romantic interests of the wintersmith while playing the role of the Summer Lady at the Autumn Morris Dance. She is at first ambivalent towards the wintersmith, unnerved by the attention, but also somewhat flattered that she has caught the eye of a godlike being. The wintersmith continues 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, manages to control the wintersmith for a time, however, eventually he gains the upper hand and brings a record-breaking snow and cold to the Chalk in what should be early spring, threatening the new lambs. She later melts 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. After Miss Treason's death, she is briefly apprenticed to Nanny Ogg before returning to the Chalk and assuming her anointed position as the Witch of the Chalkland.
Tiffany has shown skill in many of the same areas of magic as Granny Weatherwax (though generally to a lesser degree): she has prodigiously mastered the art of Borrowing (stepping outside one's self), though she didn't recognise it at the time, and merely used it as a means of viewing herself when without a mirror. The resulting vacancy of her body was what attracted the hiver to possess her. In Wintersmith, she demonstrates a high level of skill in the art of magical self-concealment, and also learns how to absorb heat from any available source (including the sun itself), store it within her body and later project it out into the world. She generally preceeds the use of the latter art with a sort of mantra, in which she states that she willingly chooses to undertake the dangerous action, and is prepared to accept full responsibility for all its consequences. Also like Granny, she has great difficulty in constructing the magical devices known as 'shambles', though unlike Granny, she later overcomes this obstacle.
She is very skilled 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 encounter with 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.
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 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.