William Lewis Manly (April 6, 1820 – February 5, 1903) was an American pioneer of the mid-19th century.
He was first a fur hunter, a guide of westward bound caravans, a seeker of gold, and then a farmer and writer in his later years.
He wrote an autobiography, first published with the title From Vermont to California, then a second edition with the title Death Valley in '49, that tells of the pioneer experience in the Far West, in particular the 1848 California Gold Rush.