Richard Warrington Baldwin Lewis (November 1, 1917 - June 13, 2002) was an American literary scholar and critic. He gained a wider reputation when he won a 1976 Pulitzer Prize for Biography or Autobiography, the first National Book Critics Circle Award for nonfiction, and a Bancroft Prize for his biography of Edith Wharton. The New York Times called the book "a beautifully wrought, rounded portrait of the whole woman, including the part of her that remained in shade during her life" and said that the "expansive, elegant biography ... can stand as literature, if nothing else."

He was the Neil Gray Professor of English and American Studies at Yale University, where he taught from 1959 until his retirement in 1988; from 1966 to 1972, he was master of Yale's Calhoun College. From 1954 to 1959 he taught at Rutgers–Newark. In 1988 Lewis received a Litt.D. from Bates College. A member of the American Academy of Arts & Sciences, Lewis received its Gold Medal for Biography in 2000.

Lewis is generally considered one of the founders of the academic field of American Studies. His interests ranged from criticism of American and European writers to biography and artistic criticism. He is associated with John William Ward.

Lewis' career as critic involved him in the lives of many influential American and European thinkers and writers. Lewis received his doctoral degree from the University of Chicago, where he studied under Norman Maclean, author of the novel A River Runs Through It and Other Stories. He and his wife and sometime co-author Nancy later became close friends with Southern writer Robert Penn Warren.

Lewis' first major work The American Adam: Innocence, Tragedy, and Tradition in the Nineteenth Century (1955) explored De Crèvecoeur's idea of the American as a "new man" - an innocent Adam in a bright new world dissociating himself from the historic past. Lewis portrayed this preoccupation as a pervasive, transforming ingredient of the American mind that shaped the consciousness of lesser thinkers as fully as it shaped the giants of the age. The book traces the Adamic theme in the writings of Ralph Waldo Emerson, Henry David Thoreau, Hawthorne, Herman Melville, Henry James and others, and in his epilogue Lewis exposes its continuing spirit in the works of F. Scott Fitzgerald, William Faulkner, Ralph Ellison, J. D. Salinger, and Saul Bellow.