Mason O'Keelan (1832-1885) was an Irish-American laborer who lived in the Foggy Bottom section of Washington DC during the late 19th century. Born in Ireland, he emigrated amid the Great Famine and settled in the United States' capital city. O'Keelan worked in Foggy Bottom's factories and raised a family of five children, including Messervy O'Keelan. O'Keelan was a Democratic voter due to his support for Catholic rights and organized labor and his opposition to the Emancipation Proclamation.