O - Sorted alphabetically

Joseph Biays Ord	Pietro di Francesco degli Orioli	Giovanni da Oriolo	Jan Frans van Orizzonte (see Bloemen)
Deodato Orlandi	Bernaert van Orley	Aleksander Orlowski	Willam Orpen
Pedro Orrente	Alfred d' Orsay	Order custom, handmade oil paintings on canvas from www.1st-art-gallery.com!	Lelio Orsi
Tommaso Orsolino	Martin Rico y Ortega	Abraham Ortelius	José Benlliure Ortiz
Ortolano	Lello Orvieto	Georgius van Os	Emily Mary Osborn
William Osborne	Order custom, handmade oil paintings on canvas from www.1st-art-gallery.com!	Rodrigo de, the Younger Osona	Stanislaw Osostowicz
Master of the Osservanza	Helmer Osslund	Adriaen Jansz. Van Ostade	Allan Osterlind
Edmund Henry Osthaus	Thomas Otter	Order custom, handmade oil paintings on canvas from www.1st-art-gallery.com!	Otto Didrik Ottesen
George Martin Ottinger	Henri Ottmann	Pierre Jan van der Ouderaa	Jean-Baptiste Oudry
Walter William Ouless	Pierre Outin	Pierre Justin Ouvrie	Isaak Ouwater
Johann Friedrich Overbeck	Order custom, handmade oil paintings on canvas from www.1st-art-gallery.com!	William Owen