Dante Alighieri. Greatest poet of all time? Some people think so, and Eliot is one of them. You'd be doing yourself a big favor if you read Canto 3 of Dante's Inferno after reading "The Hollow Men."
First, because Eliot's poem seems to be about the same group of cowardly, selfish, "small-souled" individuals that Dante describes. Second, because Dante is awesome and Canto 3 has disgusting, can't-miss-it descriptions of people being stung by wasps and walking on earthworms. The constant reference to "eyes" in "The Hollow Men" poem also parallels the importance of the eyes of Dante's lover Beatrice in the Paradiso. Most, if not all, of Eliot's most famous poems are littered with subtle references to Dante.