Agnes Robertson Arber FRS (23 February 1879 – 22 March 1960) was a British plant morphologist and anatomist, historian of botany and philosopher of biology. She was born in London but lived most of her life in Cambridge, including the last 51 years of her life. She was the first woman botanist to be elected as a Fellow of the Royal Society (21 March 1946, at the age of 67) and the third woman overall. She was the first woman to receive the Gold Medal of the Linnean Society of London (24 May 1948, at the age of 69) for her contributions to botanical science.