Susan Mary Cooper is an English author of children's books. She is best known for The Dark Is Rising, a contemporary fantasy series set in England and Wales, which incorporates British mythology such as the Arthurian legends and Welsh folk heroes. For that work, in 2012 she won the lifetime Margaret A. Edwards Award from the American Library Association, recognizing her contribution to writing for teens. In the 1970s two of the five novels were named the year's best English-language book with an "authentic Welsh background" by the Welsh Books Council. In 2024, the Science Fiction and Fantasy Writers Association named her the 40th Damon Knight Memorial Grand Master in recognition of her significant contributions to the literature of science fiction and fantasy. 

The Dark Is Rising Sequence is a series of five contemporary fantasy novels for older children and young adults that were written by the British author Susan Cooper and published from 1965 to 1977. The first book in the series, Over Sea, Under Stone, was originally conceived as a stand-alone novel, and the sequence gets its name from the second novel in the series, The Dark Is Rising. The Dark Is Rising Sequence is used as an over-arching title in several omnibus, boxed-set, and coordinated editions; but the title of The Dark is Rising is also used for the whole series.