Cassia "Joy" Cowley, DCNZM, OBE (born in Levin, 7 August 1936) is a New Zealand author of novels, short stories, and children's fiction.
Her first novel, Nest in a Fallen Tree (1967), was converted into the 1971 film The Night Digger by Roald Dahl. Following its success in the United States, Cowley wrote several works for adults: her novels Man of Straw (1972), Of Men and Angels (1972), The Mandrake Root (1975), and The Growing Season (1979) typically focused on families dealing with issues such as marital infidelity, mental illness, and death. Cowley has also published several collections of short stories, including Two of a Kind (1984) and Heart Attack and Other Stories (1985).
Cowley is known primarily for her children's fiction. Her children's novel The Silent One (1981), was made into a 1985 film; other works include Bow Down Shadrach (1991) and its sequel Gladly, Here I Come (1994). She has written 41 picture books, which include The Duck in the Gun (1969), The Terrible Taniwha of Timberditch (1982), Salmagundi (1985), and The Cheese Trap (1995). The Duck in the Gun and Salmagundi are explicitly anti-war books.
Cowley has been actively involved in teaching early reading skills and helping those with reading difficulties, in which capacity she has written approximately 500 basal readers (termed reading books in her native New Zealand).
In 1992 Cowley was awarded an OBE for services to children's literature; the following year she was granted an honorary doctorate (D.Litt) from Massey University. In 2005 she was awarded a DCNZM (A Damehood in the old honour system).
The Joy Cowley Award was established in her honour in 2002.
Cowley has been married three times, to Ted Cowley (1956-1967, died 2008), Malcolm Mason (1970-1985), dead, and Terry Coles (1989-present), and has four children. She currently lives in Wellington, New Zealand.