Conor Myles John O'Brien, 18th Baron Inchiquin (born 17 July 1943) is the holder of a hereditary peerage in the Peerage of Ireland.
He is the son of Fionn Myles Maryons O'Brien (28 October 1903 – 2 August 1977) and Josephine Reine Bembaron (died 27 October 2011). Fionn was the son of Lucius William O'Brien, 15th Baron of Inchiquin and Ethel Jane Foster. He was educated at Radley College, Abingdon, Oxfordshire and at Loughborough College, Leicestershire. He fought in the Second World War rising to Flight Lieutenant in 1941 in the service of the Royal Air Force Volunteer Reserve.
Conor Myles John O'Brien was educated at Eton, he succeeded to the peerage on the death of his uncle, Phaedrig O'Brien, 17th Baron Inchiquin, in 1982. In 1998, he visited Antioch, California for St. Patrick's Day and Antioch's first St. Patrick's Day Crinniu, hosted by then-Councilman Allen Payton and the city's council proclaimed "Sir Conor O'Brien Day". He married Helen Regina Farrell in and together they have two children, The Hon. Slaney O'Brien and The Hon. Lucia O'Brien.