King Coal is a 1917 novel by Upton Sinclair that describes the poor working conditions in the coal mining industry in the western United States during the 1910s, from the perspective of a single protagonist, Hal Warner. As in his earlier work, The Jungle, Sinclair uses the novel to express his socialist viewpoint. The book is based on the 1914-1915 Colorado coal strikes. The sequel to King Coal was posthumously published under the title, The Coal War.