The American poet Sylvia Plath always comes to mind first for this. Her collection 'Ariel' is just devastating in its raw confrontation with despair, mental anguish, and death. The imagery is so sharp it feels like it could cut you—that famous 'darkness' in 'Daddy' isn't just a mood, it's a physical presence. She doesn't just describe darkness; she sculpts it out of language in a way that feels almost violent. It's not a comfortable read, but it's a masterclass in channeling personal torment into universal art.
Moving across the Atlantic, Thomas Hardy’s poems often get overshadowed by his novels, but his poetic work is profoundly bleak. He had this cosmic pessimism, a view of a universe governed by an indifferent 'Immanent Will.' Poems like 'The Convergence of the Twain' about the Titanic, or 'During Wind and Rain,' find darkness not in personal psyche but in the cruel, ironic machinery of fate and time. His darkness feels colder, more intellectual, and in some ways more hopeless because there's no malevolent force to rage against—just emptiness.
For a more modern, visceral take, the Polish poet Wisława Szymborska often explored dark themes with a chilling, detached precision. In a poem like 'The Terrorist, He Watches,' she inhabits the mind of a bomber awaiting an explosion, and the clinical, almost bureaucratic observation of impending catastrophe is far more unsettling than any gothic description. Her darkness is in the quiet, awful logic of human cruelty and indifference.
Edgar Allan Poe is the obvious cornerstone, of course. While his popular reputation is for macabre stories, poems like 'The Raven' and 'Annabel Lee' established a whole aesthetic of melodic, mournful darkness—the beauty found in loss and decay. His influence is so pervasive he sometimes gets taken for granted, but that musical, obsessive quality is foundational.
Finally, I’d toss in the name of Federico García Lorca. His 'Romancero Gitano' and later 'Poet in New York' are saturated with a very specific, earthy darkness—moon, blood, death, and a stifling sense of tragic destiny. His 'duende,' that concept of a dark, passionate spirit in art, is practically a philosophy of how to access profound, painful beauty. Reading him feels like being pulled into a deep, folkloric well.