Rupert Everett Billingham FRS (15 October 1921 – 16 November 2002) was a British biologist who did significant research in the fields of reproductive immunology and organ transplantation. "He made numerous fundamental contributions to our modern knowledge of the mechanisms of graft rejection and how to prevent it, and he analysed some of the mechanisms responsible for the survival of the mammalian foetus in an immunologically hostile environment".