Robert William Johnstone CBE, FRCSEd, FRSE, FRCOG, (11 August 1879– 27 November 1969) was a Scottish obstetrician and gynaecologist. For some 20 years he was Professor of Midwifery and Gynaecology at the University of Edinburgh. He was a founding Fellow and subsequently vice-president of the Royal College of Obstetricians and Gynaecologists. He served as president of the Royal College of Surgeons of Edinburgh from 1943 to 1945.