Jenny Nimmo is a British author of children's books, including fantasy and adventure novels, chapter books, and picture books. Born in England, she has lived mostly in Wales for 40 years. She is probably best known for two series of fantasy novels: The Magician Trilogy (1986–1989), contemporary stories rooted in Welsh myth, and Children of the Red King (2002–2010), featuring schoolchildren endowed with magical powers. The Snow Spider, first of the Magician books, won the second annual Nestlé Smarties Book Prize and the 1987 Tir na n-Og Award as the year's best originally English-language book with an authentic Welsh background. The Stone Mouse was highly commended for the 1993 Carnegie Medal. Several others of hers have been shortlisted for children's book awards.

Jenny Nimmo was born in Windsor, Berkshire, England and educated at boarding schools in Kent and Surrey from the age of six until the age of sixteen, when she ran away from school to become a drama student/assistant stage manager with Theater South East. She graduated and acted in repertory theater in various towns and cities: Eastbourne, Tunbridge Wells, Brighton, Hastings, and Bexhill. She left Britain to teach English to three Italian boys in Amalfi, Italy. On her return, she joined the BBC, first as a picture researcher, then as an assistant floor manager, studio manager (news) then finally a director/adaptor with Jackanory (a BBC storytelling program for children). She left BBC to marry Welsh artist David Wynn Millward.