"The Constant Gardener" is a 2001 novel by British author John le Carré. The novel tells the story of Justin Quayle, a British diplomat whose activist wife is murdered. Believing there is something behind the murder, he seeks to uncover the truth and finds an international conspiracy of corrupt bureaucracy and pharmaceutical money.

The plot was vaguely based on a real-life case in Kano, Nigeria. The book was later adapted into a feature film in 2005.