Who wrote elegy on the death of W.B Yeats?

W. H. Auden's “In Memory of W. B. Yeats” (1939) is one of his most celebrated poems.
It enjoys a critical reputation as the finest poetic elegy written in English in the twentieth century, a work that boldly recast the conventions of formal elegiac verse for a disenchanted modern age.

In Memory of W. B. Yeats
W. H. Auden

"He disappeared in the dead of winter:
The brooks were frozen, the airports almost deserted,
And snow disfigured the public statues;
The mercury sank in the mouth of the dying day.
What instruments we have agree
The day of his death was a dark cold day."

Source: Poetryfoundation