Robert Anthony "Robin" Weiss (born 20 February 1940) is a British molecular biologist, Emeritus Professor of Viral Oncology at University College London and a member of the Nuffield Council on Bioethics. His research has focused on retroviruses and he is noted for important discoveries related to HIV. He is a Fellow of the Royal Society and an Honorary Fellow of the Royal College of Physicians. In 2001 he was awarded the M. W. Beijerinck Prize for Virology for his work on retroviruses. In 2007 he was awarded the Ernst Chain Prize for pioneering "our understanding of HIV and AIDS".