William Dyer (born 1875) is the narrator of At the Mountains of Madness, he is a professor of geology at Miskatonic University and a leader of the disastrous Pabodie Expedition to Antarctica in 1930–31. Only his last name is mentioned in the text of Mountains, though he is fully identified in Lovecraft's "The Shadow Out of Time", where he accompanies an expedition to Australia's Great Sandy Desert.