A Regius Professor is a university professor who has, or originally had, royal patronage or appointment. They are a unique feature of academia in the United Kingdom and Ireland. The first Regius Professorship was in the field of medicine, and founded by the Scottish King James IV at the University of Aberdeen in 1497. Regius chairs have since been instituted in various universities, in disciplines judged to be fundamental and for which there is a continuing and significant need. Each was established by an English, Scottish, or British monarch, and following proper advertisement and interview through the offices of the university and the national government, the current monarch still appoints the professor. This royal imprimatur, and the relative rarity of these professorships, means a Regius chair is prestigious and highly sought-after.

Sir Simon Charles Wessely is a British psychiatrist. He is Regius Professor of Psychiatry at the Institute of Psychiatry, King's College London and head of its department of psychological medicine, vice dean for academic psychiatry, teaching and training at the Institute of Psychiatry, as well as Director of the King's Centre for Military Health Research. He is also honorary consultant psychiatrist at King's College Hospital and the Maudsley Hospital, as well as civilian consultant advisor in psychiatry to the British Army. He was knighted in the 2013 New Year Honours for services to military healthcare and to psychological medicine. From 2014 to 2017, he was the elected president of the Royal College of Psychiatrists.