Peter John Barrett NZAM (born 11 August 1940) is a New Zealand geologist who came to prominence after discovering the first tetrapod fossils in Antarctica in 1967.

His 1968 doctoral thesis at the Institute of Polar Studies had the title The post-glacial Permian and Triassic Beacon rocks in the Beardmore Glacier area, central Transantarctic Mountains, Antarctica.

[4] After finishing his PhD, he took up a postdoctoral fellowship at Victoria University of Wellington to run an Antarctic expedition.

[8] Barrett's notable students include Nancy Bertler and Rob McKay.

[9] In 1978, Barrett was awarded the Polar Medal, for good services as a member of New Zealand expeditions to Antarctica in 1974–1975.