Gordon Leslie Ada AO, FAA (6 December 1922 – 25 September 2012) was an Australian biochemist best known for his seminal contributions to virology and immunology and his long leadership of the Department of Microbiology at the John Curtin School of Medical Research at the Australian National University, where Peter C. Doherty and Rolf Zinkernagel performed their Nobel winning research in his department.
From 1962 he focused on immune reactions, demonstrating that antigens are not present in antibody-producing cells, in support of Burnet's clonal selection theory.
In 1968 Ada was appointed head of the Microbiology Department at the John Curtin School of Medical Research at the Australian National University, taking over from Frank Fenner.
His latter years in science were spent as a visiting professor at the John Curtin School, where he was involved in the development of a candidate HIV vaccine.
During that time he also wrote a very readable and informative popular science book on immunization, Vaccination: The Facts, the Fears, the Future published in 2001.