All Names
- O'Dea, Thomas
- O'Neill, G. B.
- Oakley & Thompson (2)
- Oakley, Frank F.
- Oertel, Johannes Adam Simon, 1823-1909
- Ogden, Henry Alexander, 1856-1936 (6)
- Opie, John, 1761-1807
- Opper, Frederick Burr, 1857-1937
- Ormsby, Waterman Lilly, 1834-1908 (2)
- Orr, Louis, 1879-1966 (11)
- Ostade, Adriaen van, 1610-1685
- Otis, Bass, 1784-1861
- Otis, C. N.
- Ozanne, Jna. Fca. (Jeanne Françoise), 1735-1795
- Ozanne, Nicolas-Marie, 1728-1811
