American teacher, novelist, and critic known for his definitive biographies of Ernest Hemingway and Percy Bysshe Shelley.

Baker received his Ph.D. from Princeton University (1940) and became professor of English there in 1951. His book Shelley's Major Poetry: The Fabric of a Vision (1948) dwells on Shelley's inner self as visible in his poetry and largely ignores the exterior circumstances of the poet's life. Baker examines Shelley's work within a literary chronology and traces the poet's personal changes through his poems, revealing a many-faceted man. His widely acclaimed Hemingway: The Writer as Artist (1952) is regarded as one of the definitive works on the writer. It provides a portrait of an artist and his generation and a critique of Hemingway's novels in moral and aesthetic terms. Baker's Ernest Hemingway: A Life Story (1969) is an authoritative biography of the writer. Baker also edited Hemingway's letters into a comprehensive volume.