Robert Millner Shackleton FRS (30 December 1909 – 3 May 2001) was a British field geologist who developed an interest in the geology of East Africa. He initiated structural studies across orogenic belts in Tanzania-Zambia-Malawi (in the late 1960s), major studies across the Limpopo Belt and adjacent Archaean greenstone belts of Zimbabwe-Botswana-South Africa (in the 1970s) and projects across the orogenic systems of Egypt, Sudan and Kenya (in the early 1980s). Just prior to his death he was working on a detailed compilation of the Precambrian geology of East Africa. At the age of 75 he led a Royal Society geological traverse across Tibet, in collaboration with the Academica Sinica, Beijing.