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. She went on to complete a doctorate at Harvard University, with John Rawls as supervisor. During the 1970s she taught at Barnard College, the women's college in Columbia University, New York City. In 1977 she returned to Britain and took up a post at the University of Essex; she was Professor of Philosophy there when she became Principal of Newnham College, Cambridge in 1992.
She is an Emeritus Professor of Philosophy at the University of Cambridge, a former President of the British Academy (2005–2009) and chaired the Nuffield Foundation (1998–2010). In 2003, she was the founding President of the British Philosophical Association (BPA). In 2013 she held the Spinoza Chair of Philosophy at the University of Amsterdam. Until October 2006, she was the Principal of Newnham College, Cambridge, and she was in chair in the Equality and Human Rights Commission until April 2016. O'Neill's work has earned her numerous honors and awards, including the million-dollar Berggruen Prize.