William Butler Yeats was an Irish poet, playwright, and one of the foremost figures of 20th century literature. He was a driving force behind the Irish Literary Revival and was one of the few writers to be awarded the Nobel Prize in Literature in 1923. Yeats was known for his exploration of themes of love, death, and the supernatural, as well as his use of symbolism and mythological allusions. His works are still widely read and studied today.