Robert Penn Warren (April 24, 1905 – September 15, 1989) was an American poet, novelist, and literary critic and was one of the founders of New Criticism. He was also a charter member of the Fellowship of Southern Writers. He founded the influential literary journal The Southern Review with Cleanth Brooks in 1935.

Born in Guthrie, Kentucky, Warren graduated from Clarksville High School in Clarksville, Tennessee, Vanderbilt University in 1925 and the University of California, Berkeley in 1926. Warren later attended Yale University and obtained his B. Litt. as a Rhodes Scholar from New College, Oxford, in England in 1930. He also received a Guggenheim Fellowship to study in Italy during the rule of Benito Mussolini. That same year he began his teaching career at Southwestern College (now Rhodes College) in Memphis, Tennessee.

While still an undergraduate at Vanderbilt, Warren became associated with the group of poets there known as the Fugitives, and somewhat later, during the early 1930s, Warren and some of the same writers formed a group known as the Southern Agrarians. He contributed "The Briar Patch" to the Agrarian manifesto I'll Take My Stand. In "The Briar Patch," Warren defends racial segregation. However, Warren recanted these views in an article on the Civil Rights Movement, "Divided South Searches Its Soul," which appeared in the July 9, 1956 issue of Life magazine. A month later, Warren published an expanded version of the article as a small book titled Segregation: The Inner Conflict in the South.  He subsequently adopted a high profile as a supporter of racial integration. In 1965, he published Who Speaks for the Negro?, a collection of interviews with black civil rights leaders including Malcolm X and Martin Luther King, thus further distinguishing his political leanings from the more conservative philosophies associated with fellow Agrarians such as Tate, Cleanth Brooks, and particularly Davidson.

Warren's best-known work is All the King's Men, a novel that won the Pulitzer Prize in 1947. Warren served as the Consultant in Poetry to the Library of Congress, 1944–1945 (later termed Poet Laureate), and won two Pulitzer Prizes in poetry, in 1958 for Promises: Poems 1954-1956 and in 1979 for Now and Then. Promises also won the annual National Book Award for Poetry.  In 1981, Warren was selected as a MacArthur Fellow and later was named as the first U.S. Poet Laureate Consultant in Poetry on February 26, 1986. Warren was co-author, with Cleanth Brooks, of Understanding Poetry, an influential literature textbook. It was followed by other similarly co-authored textbooks, including Understanding Fiction and Modern Rhetoric, which adopted what can be called a New Critical perspective.