Onora Sylvia O'Neill, Baroness O'Neill of Bengarve CH CBE FRS FBA FMedSci (born 23 August 1941) is a philosopher and a crossbench member of the House of Lords.
The daughter of Sir Con O'Neill, she was educated partly in Germany and at St Paul's Girls' School, London, before studying philosophy, psychology and physiology at Somerville College, Oxford.