Brian O’Sullivan is a Professor in the Department of Radiation Oncology and Department of Otolaryngology / Head and Neck Surgery, University of Toronto, Princess Margaret Hospital (PMH) Toronto, Canada, and the Department of Radiation Oncology, University of Montreal. He graduated from University College Dublin, Ireland, and completed a fellowship in medical oncology, and residency and clinical fellowship in radiation oncology, all at PMH. He has been involved in head and neck cancer and sarcoma academic activities for many years. He is immediate past Chair of H&N Oncology at PMH, immediate past radiation oncology Chair of the US NCI Head and Neck Steering Committee, current Chair of the Head and Neck Educational Committee of the American Society of Clinical Oncology (ASCO), and a past President of the Connective Tissue Oncology Society (CTOS). He has more than 600 publications, more than 450 of which are peer-reviewed, and edited 12 oncology textbooks. He is a member of the TNM Committee of the Union for International Cancer Control (UICC), Chair of the UICC Prognostic Factors Sub-Committee and is UICC head and neck cancer and soft tissue / bone sarcoma liaison to the American Joint Committee on Cancer (AJCC). He is a Commissioner of the International Commission on Radiation Units and Measurement (ICRU). His professional honours are numerous but among many include the Gold Medal of The Juan A del Regato Foundation; the Award of Honor for the Annual Oration in Radiation Oncology of RSNA; and the American Society of Radiation Oncology (ASTRO) Gold Medal.