Alphabetical Index of Creators - O
- O'Brien Galleries (Chicago, Ill.)
- O'Connor, Francis V., 1937-
- O'Connor, Harold, 1941-
- O'Connor, Madeline, 1931-2002
- O'Doherty, Brian, 1928-
- O'Donovan, William Rudolph, 1844-1920
- O'Grady, Lorraine, 1934-
- O'Hanlon, Ann Rice, 1908-1998
- O'Hanlon, Richard E. (Richard Emmett), 1906-1985
- O'Hara, Frederick, 1904-1980
- O'Hara, Ruth
- O'Keeffe, Georgia, 1887-1986
- O'Neil, John, 1915-2004
- O'Neill, Clarence J.
- O'Neill, Kelly
- O'Sullivan, Judith
- O'Toole, James St. L. (James St. Laurence), 1895-
- O'Toole-Ewald Art Associates (New York, N.Y.)
- OK Harris Works of Art (Gallery: New York, N.Y.)
- Oakes, Edward Everett, 1891-1960
- Oakland Museum
- Oakley, Thornton, 1881-1953
- Oakley, Violet, 1874-1961
- Oberteuffer, Karl Amiard, 1908-1958
- Objects Gallery (San Antonio, Tex.)
- Oddie, Walter Mason, 1807-1865
- Ogden, Henry Alexander, 1856-1936
- Ogunquit Art Association
- Ohashi, Yutaka, 1923-1989
- Ohrstrom, Terry Anne, 1946-
- Ojeda, Naul, 1939-2002
- Okada, Frank S. (Frank Sumio), 1931-2000
- Okada, Kenzo, 1902-1982
- Okubo, Miné, 1912-2001
- Oldenburg, Claes, 1929-
- Oldfield, Otis, 1890-1969
- Olds, Elizabeth, 1896-1991
- Olinsky, Ivan G. (Ivan Gregorewitch), 1878-1962
- Olitski, Joan C., 1937-
- Olitski, Jules, 1922-2007
- Oliva, Tomás, 1930-1996
- Oliveira, Nathan, 1928-2010
- Oliver, James, fl. 1865-1890
- Oliver, Steven H., 1941-
- Ollman, John E., 1942-
- Olmsted, Anna Wetherill, 1888-1981
- Olmsted, Fred, 1911-
- Olmsted, Frederick Law, 1822-1903
- Olney, Charles F. (Charles Fayette), 1831-1903
- Olsoff, Wendy, 1956-
- Olyphant, Robert M., 1824-1918
- Onderdonk family
- Onderdonk, Julian, 1882-1922
- Onslow-Ford, Gordon, 1912-2003
- Opie, Catherine, 1961-
- Oppenheim, Dennis, 1938-2011
- Oppenhimer, Ann Frederick
- Opper, John, 1908-1994
- Ord, George, 1781-1866
- Orear, Gordon, 1923-
- Oregon Public Broadcasting
- Oren, Michel
- Organization of Art Sponsors
- Organization of Independent Artists (New York, N.Y.)
- Origins Gallery
- Orlowsky, Lillian, 1914-2004
- Ormond, Richard L., 1939-
- Orozco, Syliva, 1954-
- Orr, Elliot, 1904-1997
- Orr, Louis, 1879-1966
- Orswell, Lois Dailey, 1904-1998
- Ortega, Tony, 1958-
- Ortman, George Earl, 1926-
- Ortmayer, Constance, 1902-1988
- Orton, Edward, 1863-1932
- Ory, Norma R.
- Osborn, David S.
- Osborn, Robert Chesley, 1904-1994
- Osborne, Elizabeth, 1936-
- Osborne, Lue, 1889-1968
- Osgood, Jere, 1936-
- Osolnik, Rude, 1915-2001
- Ossorio, Alfonso A., 1916-1990
- Ostrowsky, Abbo, 1889-1975
- Ostrum, Sarepta Pierpont, 1922-
- Osver, Arthur, 1912-2006
- Otis, Bass, 1784-1861
- Otis, George Demont, 1879-1962
- Ott, Peterpaul, 1895-1992
- Outterbridge, John Wilfred, 1933-
- Overby, Robert, 1935-1993
- Overmyer, Grace
- Overstreet, Joe, 1933-
- Owen Gallery
- Owen, C. B. (Clara Belle), 1854-1955
- Owen, Jane Blaffer, 1915-2010
- Owen, Robert Emmett, 1878-1957
- Owens, Gene, 1931-
- Ox-Bow Summer School of Painting