Professor Roger Stanley Williams, CBE is a British medical doctor, specialising in hepatology (treatment of the liver). He is currently Director of the Institute of Hepatology at UCL University College, London. A formidable and dynamic World leader in the field, he has inspired international research in diseases of the liver.

Williams was part of the medical team that performed the first liver transplant in the UK in 1968.

He is recently well known for treating footballer George Best, who suffered various liver ailments after a battle with alcoholism. Williams supervised a liver transplant on Best in 2002. . Best, however, ignored advice not to drink and died in 2005.