Denis Maurice O'Conor (Irish: Donnchadh Muirgheas Ó Conchubhair Donn; 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. He was appointed High Sheriff of Roscommon for 1865.
He married Ellen Isabella, the eldest daughter of Rev. W. T. Kevill Davies of Croft Castle, Herefordshire with whom he had a son.