Dimity is a young witch in apprenticed training, and a member of Anagramma's coven. She appears in A Hat Full of Sky, in which she sets fire to her own hat, and in Wintersmith, she makes a toothache cure explode. Her name is similar to that of Jill Murphy's character Mildred Hubble of The Worst Witch novels, although Pratchett says this was not intentional.
Currently no pictures of Dimity exist ...