Robert Allen Dyer (21 September 1900 in Pietermaritzburg – 26 October 1987 in Johannesburg) was a South African botanist and taxonomist, working particularly on Amaryllidaceae and succulent plants, contributing to and editing of Bothalia and Flowering Plants of Africa and holding the office of Director of the Botanical Research Institute in Pretoria from 1944 to 1963.

After doing a three-year stint (1931-1934) as liaison officer with the Royal Botanic Gardens, Kew, he was transferred to the National Herbarium in Pretoria.

After retiring in 1963, he continued working at the Institute, devoting his time to producing Genera of Southern African Flowering Plants.

His last major work dealt with Ceropegia, Brachystelma and Riocreuxia and appeared in Flora of Southern Africa in 1981.

His collected botanical specimens number over 6000 and are lodged in Pretoria, Grahamstown, Kew and the Bolus Herbarium.