William Styron, the Pulitzer Prize-winning author of The Confessions of Nat Turner and other novels whose explorations of the darkest corners of the human mind and experience were charged by his own near-suicidal demons, died on Wednesday. He was 81. Styron’s daughter, Alexandra, said the author died of pneumonia at a hospital in Martha’s Vineyard, Mass. Styron, who had homes in Martha’s Vineyard and Connecticut, had been in failing health for a long time. “This is terrible,” said Kurt Vonnegut, a longtime friend. “He was dramatic, he was fun. He was strong and proud and he was awfully good with the language. I hated to see him end this way.” A handsome, muscular man, with a strong chin and wavy dark hair that turned an elegant white, Styron was a Virginia native whose obsessions with race, class and personal guilt led to such tormented narratives as Lie Down In Darkness and The Confessions of Nat Turner, which won the Pulitzer despite protests that the book was racist and inaccurate. His other works also included Sophie’s Choice, the award-winning novel about a Holocaust survivor from Poland, and A Tidewater Morning.