William Butler Yeats[a] (13 June 1865 – 28 January 1939) was an Irish poet, dramatist, writer and one of the foremost figures of 20th-century literature. He was a driving force behind the Irish Literary Revival and became a pillar of the Irish literary establishment who helped to found the Abbey Theatre. In his later years he served two terms as a Senator of the Irish Free State.

A Protestant of Anglo-Irish descent, Yeats was born in Sandymount and was educated in Dublin and London and spent childhood holidays in County Sligo. He studied poetry from an early age, when he became fascinated by Irish legends and the occult. These topics feature in the first phase of his work, lasting roughly from his student days at the Metropolitan School of Art in Dublin until the turn of the 20th century. His earliest volume of verse was published in 1889, and its slow-paced and lyrical poems display debts to Edmund Spenser, Percy Bysshe Shelley and the poets of the Pre-Raphaelite Brotherhood.

From 1900 his poetry grew more physical, realistic and politicised. He moved away from the transcendental beliefs of his youth, though he remained preoccupied with some elements including cyclical theories of life. He had become the chief playwright for the Irish Literary Theatre in 1897, and early on promoted younger poets such as Ezra Pound. Yeats was awarded the Nobel Prize in Literature in 1923. His major later works include 1928's The Tower and Words for Music Perhaps and Other Poems, published in 1932.