L.O.. 1 portrait.
Jonathan Oakes (1961-). 1 portrait.
Harry Lawrence Oakley (1882-1960). 23 portraits.
Octavius Oakley (1800-1867). 6 portraits.
Mark Oates (active 1799). 1 portrait.
Colin O'Brien (1940-). 1 portrait.
Joanne O'Brien. 3 portraits.
Humphrey Ocean (Humphrey Anthony Erdeswick Butler-Bowdon) (1951-). 9 portraits.
Paul O'Connell. 7 portraits.
James Arthur O'Connor (1792-1841). 1 portrait.
M. O'Connor (active circa 1834). 3 portraits.
Francesca Odell. 3 portraits.
Odieuvre (active 1742-1748). 1 portrait.
Alexander O'Driscoll (active 1840-1844). 3 portraits.
Geo. E. Oertel. 1 portrait.
Ino I. Offord (active 1897). 1 portrait.
Chris Ofili (1968-). 1 portrait.
David Ogborne (died 1800 or 1801). 5 portraits.
John Ogborne (1755-1837). 20 portraits.
Perry Ogden (1961-). 2 portraits.
M. Ogle (active 1826). 1 portrait.
Thomas Ogle (active 1860s). 1 portrait.
Samuel Oglesby. 1 portrait.
Ogles, Duncan & Cochran (active 1815). 1 portrait.
Kane O'Hara (active circa 1803). 1 portrait.
Nicholas Okes (active in London 1606-39). 2 portraits.
Samuel Okey (active 1721-1756). 2 portraits.
Samuel Okey (1741?-in or after 1780). 6 portraits.
Dominic Old (1963-). 8 portraits.
Anton Oleszczynski (1794-1879). 1 portrait.
Reverend Thomas Olive (circa 1748-1799). 2 portraits.
Archer James Oliver (1774-1842). 11 portraits.
Isaac Oliver (circa 1565-1617). 70 portraits.
John Oliver (1616-1701). 2 portraits.
Mabel Oliver. 1 portrait.
Peter Oliver (circa 1594-1647). 17 portraits.
Sydney Haldane Olivier, 1st Baron Olivier (1859-1943). 3 portraits.
Herbert Olivier (1861-1952). 1 portrait.
Dominick Andrew Olivieri (active 1820-1833). 1 portrait.
Alan Olley. 6 portraits.
Ruan O'Lochlan. 3 portraits.
Hans Christian Olsen (1845-1909). 1 portrait.
Sean O' Mordha. 1 portrait.
Henry Nelson O'Neil (1817-1880). 1 portrait.
Desmond O'Neill (active 1960s). 1 portrait.
George Bernard O'Neill (1828-1917). 1 portrait.
Mary O'Neill (died 1987). 1 portrait.
Terry O'Neill (1938-). 67 portraits.
The One Studio (active 1910s). 2 portraits.
F. Onwhyn (active mid 19th century). 4 portraits.
Joseph Onwhyn (active 1820-1870). 4 portraits.
Ivan Opffer (1897-1980). 21 portraits.
Amelia Opie (1769-1853). 1 portrait.
John Opie (1761-1807). 150 portraits.
Julian Opie (1958-). 6 portraits.
Opie Ltd. 1 portrait.
Moritz Daniel Oppenheim (1800-1882). 1 portrait.
Joseph Oppenheimer (1876-1967). 2 portraits.
Orchard. 1 portrait.
Bill Orchard (1940-). 1 portrait.
Robert Orchard (active 1803). 1 portrait.
Sir William Quiller Orchardson (1832-1910). 5 portraits.
Cuthbert Julian Orde (1888-1968). 1 portrait.
Bryan Organ (1935-). 15 portraits.
Giovanni Orlandi (active 1590-1640). 1 portrait.
Daniel Orme (1766-1837). 15 portraits.
Edward Orme (1775-1848). 35 portraits.
Sir William Orpen (1878-1931). 27 portraits.
Christopher John ('Chris') Orr (1943-). 1 portrait.
William Somerville Orr & Co (active 1838-1857). 1 portrait.
Carlo Orsi (active 1881-1896). 1 portrait.
E. Ortner. 1 portrait.
Li Osborne. 2 portraits.
Malcolm Osborne (1880-1963). 8 portraits.
Walter Frederick Osborne (1859-1903). 1 portrait.
Alessandro Ossani (active 1857-1888). 3 portraits.
Osterstock. 1 portrait.
Ostervald the Elder (active 1817-1840). 1 portrait.
Tim O'Sullivan (1959-). 4 portraits.
John Oswald (active 1737-1743). 4 portraits.
Frederick Ottens (active 18th century). 1 portrait.
Thomas Ottley (active 1842-1915). 1 portrait.
Otto. 2 portraits.
F. Otto's School of Photography (active 1860s). 1 portrait.
P. Oudry (active 1578). 1 portrait.
Walter William Ouless (1848-1933). 40 portraits.
Sir William Ouseley (1767-1842). 3 portraits.
John Outrim (born 1810-active 1874). 3 portraits.
Horace Ové (1939-). 12 portraits.
Jeff Overs. 3 portraits.
Henry Overton (1675 or 1676-1751). 9 portraits.
John Overton (1639 or 1640-1713). 8 portraits.
Mary Overton (active 1745-1748). 1 portrait.
Philip Overton (circa 1680-1745). 16 portraits.
Thomas Overton (active 1818-1838). 3 portraits.
Arthur A. Owen. 1 portrait.
John Owen (active 1860s-1890s). 1 portrait.
Mike Owen (1954-). 32 portraits.
William Owen (1769-1825). 97 portraits.
Chris Owens. 1 portrait.
Oxford University Press. 1 portrait.
The Oxford School of Photography & Colouring (active 1860s). 2 portraits.
David Jowett Greaves Oxtoby (1938-). 2 portraits.
