Sir Peter John Ratcliffe, FRS, FMedSci is a British physician-scientist who is trained as a nephrologist. He was a practising clinician at the John Radcliffe Hospital, Oxford and Nuffield Professor of Clinical Medicine and head of the Nuffield Department of Clinical Medicine at the University of Oxford from 2004 to 2016. He has been a Fellow of Magdalen College, Oxford since 2004. In 2016 he became Clinical Research Director at the Francis Crick Institute, retaining a position at Oxford as a member of the Ludwig Institute of Cancer Research and director of the Target Discovery Institute, University of Oxford.