| Honorific Prefix: | The Right Honourable |
| The Lord Rathcavan | |
| Office: | Member of the House of Lords |
| Status: | Lord Temporal |
| Term Label: | as a hereditary peer |
| Term Start: | 30 December 1994 |
| Predecessor: | The 2nd Baron Rathcavan |
| Term End: | 11 November 1999 |
| Successor: | Seat abolished |
| Birth Name: | Hugh Detmar Torrens O'Neill |
| Birth Date: | 14 June 1939 |
| Occupation: | Businessman, peer, politician |
Hugh Detmar Torrens O'Neill, 3rd Baron Rathcavan (born 14 June 1939), is a British hereditary peer and businessman who sat as a crossbencher in the House of Lords from 1994 until 1999.
He was educated at Eton College.[1]
O'Neill ran Lamont, a textile company in Northern Ireland, in the 1980s and was chairman of the Northern Ireland Tourist Board before taking on the Brasserie St Quentin in Knightsbridge in 2002.[2]