Human beings, each considered as a single actor within society
Notable Individuals
- Obama, Barack (1961- ) - Forty-fourth president of the United States
- Opitz, Edmund A. (1914-2006) - 20th century American author, longtime contributor to the Foundation for Economic Education
- Oppenheimer, Franz (1864-1943) - German sociologist and economist, author of The State
- Orwell, George (1903-1950) - British writer, author of 1984 and Animal Farm
Other Individuals
- Oglesby, Carl (1935-2011) - American writer, author of Who Killed JFK?, past president of Students for a Democratic Society
- O'Hara, Maureen (1920-2015) - Irish-born red-haired Hollywood actress, starred in The Quiet Man
- Olbermann, Keith (1959- ) - Host of the Countdown show on MSNBC
- O'Reilly, John Boyle (1840-1890) - Irish poet and activist, member of the Irish Republican Brotherhood
- O'Rourke, P. J. (1947-2022) - Political satirist, author
- Otis, James (1725-1783) - 18th century American colonial lawyer
- Otter, Butch (1942- ) - Governor of Idaho and former Congressman
- Overton, Richard - English pamphleteer and member of the Levellers
- Owen, Robert (1771-1858) - Welsh textile manufacturer, advocate of utopian socialism