The Wild Swans at Coole' is written by-

William Butler Yeats (1865-1939):
He was a poet, dramatist and critic, famous for his use of symbolism and mysticism.

Works:
-The Resurrection (1913)
-The Wild Swans at Coole (1919)
-The Cat and the Moon (1926)
-The Tower (1928)
-The Winding Stair and Other Poems (1933)

Source: An ABC of English Literature - Dr M Mofizar Rahman