A Regius Professor is a university professor in the United Kingdom or Ireland whose chair (professorship) has, or originally had, royal patronage or appointment. The first Regius Professorship was in the field of medicine, and was 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. As of 2026, there are 85 active Regius Professorships. 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.