William Butler Yeats was an Irish poet, dramatist, and writer, one of the foremost figures of 20th-century literature. He played a pivotal role in the Irish Literary Revival and, along with Lady Gregory, founded the Abbey Theatre, serving as its chief in its early years. In 1923, he was awarded the Nobel Prize in Literature, and he later served two terms as a Senator of the Irish Free State.

A Protestant of Anglo-Irish descent, Yeats was born in Sandymount, Ireland. His father was a successful portrait painter and practiced law. Yeats was educated in Dublin and London, spending his childhood holidays in County Sligo, which deeply influenced his early poetry. From an early age, he was fascinated by Irish legends and the occult, themes that prominently feature in his work. His early poetry showed influences from John Keats, William Wordsworth, William Blake, Edmund Spenser, Percy Bysshe Shelley, and the poets of the Pre-Raphaelite Brotherhood. His first volume of verse was published in 1889.

From 1900, his poetry evolved to be more physical, realistic, and politicised, moving away from the transcendental beliefs of his youth while still engaging with cyclical theories of life. He became the chief playwright for the Irish Literary Theatre in 1897 and promoted younger poets such as Ezra Pound. His major works include The Land of Heart's Desire (1894), Cathleen ni Houlihan (1902), Deirdre (1907), The Wild Swans at Coole (1919), The Tower (1928), and Last Poems and Plays (1940).