Peter Medawar wani masanin ilmin halitta dan kasar Birtaniya ne wanda ya shahara da irin gudunmawar da yake bayarwa a fannin rigakafi. An ba shi lambar yabo ta Nobel a fannin Physiology ko Medicine a cikin 1960, tare da Sir Frank Macfarlane Burnet, saboda binciken da suka yi na samun juriya na rigakafi. Baya ga aikinsa a fannin rigakafi, Medawar ya kuma shahara da rubuce-rubucensa kan kimiyya, falsafa, da fasaha.