37.

X was an American expatriate poet and critic and a major figure in the early modernist movement in poetry. His best known works include Ripostes, Hugh Selwyn Mauberley, and his unfinished 120-section epic The Cantos, published over five decades from 1917 to 1969. Of him Ernest Hemingway wrote:

"He defends [his friends] when they are attacked, he gets them into magazines and out of jail. He loans them money. ... He writes articles about them. He introduces them to wealthy women. He gets publishers to take their books. He sits up all night with them when they claim to be dying ... he advances them hospital expenses and dissuades them from suicide."

X is the person second from left. X? Also brownie points for identifying the other 3 greats.