Sir Arthur George Tansley FLS, FRS (15 August 1871 – 25 November 1955) was an English botanist and a pioneer in the science of ecology. Educated at Highgate School, University College London and Trinity College, Cambridge, Tansley taught at these universities and at Oxford, where he served as Sherardian Professor of Botany until his retirement in 1937. He founded the New Phytologist in 1902 and served as its editor until 1931.