What modernist poet won the Pulitzer Prize in 1924 and 1931 and 1937 and 1943?

Robert Frost won four Pulitzer Prizes for his books of poetry:

1924: New Hampshire: A Poem with Notes and Grace Notes

1931: Collected Poems

1937: A Further Range

1943: A Witness Tree

In 1971, Lawrance Thompson won a Pulitzer Prize for his biography, Robert Frost: The Years of Triumph, 1915 -1938.