Denis, Maurice, 1870-1943, French painter and writer on art. His paintings, usually on religious themes, have not proved so influential as his art theories. As the spokesman for symbolism and for the Nabis, Denis proposed his famous definition of painting: "Remember that a picture, before being a battle horse, a nude, an anecdote or whatnot, is essentially a flat surface covered with colors assembled in a certain order." In 1919, Denis attempted to revive the teaching of religious art and cofounded the Studios of Sacred Art. His writings include Théories (2 vol.; 1920, 1922) and Histoire de l'art religieux (1939).

Denis Maurice O'Conor (1840–26 July 1883) was an Irish politician, Member of Parliament in the Parliament of the United Kingdom.

The second son of The O'Conor Don, O'Conor was educated at Downside School and the University of London, gaining an MA in 1861 and LLD in 1866. A barrister, he was called to the bar at Middle Temple, 1866. He was a member of the Reform Club.

O'Conor served as a Liberal (pro-Home Rule) MP for County Sligo from December 1868 until his death .