William Horwood is an English novelist. His first novel, Duncton Wood, an allegorical tale about a community of moles, was published in 1980. It was followed by two sequels, forming The Duncton Chronicles, and also a second trilogy, The Book of Silence. William Horwood has also written two stand-alone novels intertwining the lives of humans and of eagles, The Stonor Eagles and Callanish , and The Wolves of Time duology. Skallagrigg, his 1987 novel about disability, love, and trust, was made into a BBC film in 1994. In addition, he has written a number of sequels to The Wind in the Willows by Kenneth Grahame.

In 2007, he collaborated with historian Helen Rappaport to produce Dark Hearts of Chicago, a historical mystery and thriller set in nineteenth-century Chicago. It was republished in 2008 as City of Dark Hearts with some significant revisions and cuts under the pen name James Conan.