Sir Simon Charles Wessely (born Sheffield, 1956) is a British psychiatrist. He is Professor of Psychological Medicine 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.