He was 87.
Leonard passed away yesterday, several weeks after suffering from a stroke.
An announcement on his website said: "Elmore passed away this morning at home, surrounded by his loving family." It did not provide any other details.
Leonard, who first wrote westerns when he gave up his advertising agency job in the 1950s before moving on to crime and suspense books, suffered a stroke on July 29.
Known by the nickname Dutch, Leonard had his commercial breakthrough in 1985 with the publication of Glitz. His following books, including Get Shorty, Out of Sight, Killshot, Bandits and Freaky Deaky, came out every year-and-a-half or so and were best-sellers.
Leonard's 47th book, Blue Dreams, was expected to be published this year.
More than 25 of Leonard's works have been made into movies or television shows, beginning with Paul Newman in the 1967 film Hombre. The western story 3:10 to Yuma and the novel The Big Bounce were each adapted for film twice.