Lady Eve Balfour (Evelyn Barbara Balfour; 1899-1990) was an English farmer, educator, organic farming pioneer, and a founding figure in the organic movement. She was one of the first women to study agriculture at an English university, graduating from the University of Reading.

The daughter of the second Earl of Balfour, she began farming in 1920, in Haughley Green, Suffolk, England. In 1939, with her friend and neighbor Alice Debenham, she launched the Haughley Experiment, the first long-term, side-by-side scientific comparison of organic and chemical-based farming.

In 1943, she published the organics classic, The Living Soil, a book combining her research with the initial findings at Haughley. In 1946, she co-founded and became the first president of the Soil Association, an international organization promoting sustainable agriculture (and the main organic farming association in the UK today). She continued to farm, write and lecture for the rest of her life.