A. O. Carpenter (born Aurelius O. Carpenter) (1836-1919) was an American photographer, writer and abolitionist. He was one of the earliest photographers in early American California, photographing Mendocino County, California. He was the son of Clarina I. H. Nichols and the father of Grace Carpenter Hudson and Grant Carpenter. Prior to moving to California, he was active in the abolitionist movement, fighting with John Brown in the Battle of Black Jack.
Aurelius Carpenter was born in 1836 in Vermont. His mother was Clarina I. H. Nichols. As a teenager, he had an apprenticeship at the Windham County Democrat, the newspaper owned by his stepfather, George Nichols.