Irish painter and printmaker. He studied at the Metropolitan School of Art in Dublin and at the Royal Hibernian Academy(1879–83), before attending the Académie Royale des Beaux-Arts in Antwerp (1883–4). He returned to Ireland but soon moved to Paris, and he continued to exhibit there until 1908.
In his earliest French landscapes O’Conor was influenced by the Impressionists. O’Conor’s preference for rich colour contrasts and thick textures came to the fore in landscapes of Brittany between 1892 and 1895 in which he applied the paint in long, parallel stripes of colour. O’Conor’s etchings are rhythmically drawn and boldly expressed linear interpretations of the landscape at Le Pouldu.
O’Conor’s later work in Brittany became more conservative, although a number of pictures of the rocky coastline from 1898 are particularly vigorous and expressionist in feeling. He moved to Paris in 1904, exhibiting for many years at the Salon d’Automne and painting numerous still-life groups, portraits and nudes, often experimenting with different approaches and techniques. Later paintings are more heavily textured his still-lifes and nudes showing extensive use of the palette-knife. Known to have had a formidable personality, O’Conor was a dominant figure among a group of artists and writers, including Clive Bell and W. Somerset Maugham. Near the end of his life O’Conor married his former model and mistress, Renée Honta.