John Steinbeck (1902 - 1968) was one of the most famous American novelists of the twentieth century. He was awarded the Nobel Prize for literature in 1962.
Steinbeck wrote in the naturalist/realist style, often about poor, working-class people. His most famous work, The Grapes of Wrath, tells the story of a poor family from Oklahoma and their journey to and subsequet struggles in California. It is often understood as a novel in defense of the poor as against the rich.
East of Eden is probably Steinbeck's most substantial work. In it Steinbeck stops looking towards social injustice as the source of evil, and instead explores the roots of evil in human psychology.