Joseph Gavin Collier FRCP (born 1942) is a British retired clinical pharmacologist and emeritus professor of medicines policy at St George's Hospital and Medical School in London, whose early research included establishing the effect of aspirin on human prostaglandins and looking at the role of nitric oxide and angiotensin converting enzyme in controlling blood vessel tone and blood pressure. Later, in his national policy work, he helped change the way drugs are priced and bought by the NHS, and ensured that members of governmental advisory committees published their conflicts of interest.