Helen May Leach ONZM (née Keedwell; 3 July 1945 – 23 January 2026) was a New Zealand academic who specialised in food anthropology. She conducted research for more than 50 years into the history of New Zealand, the archaeology and anthropology of Oceanic culture, and the social history and anthropology of culinary and horticultural practices, and wrote at least 22 books on these subjects. She was a professor emerita at the University of Otago.

Born Helen May Keedwell in Wellington on 3 July 1945, Leach was the daughter of Peggy and Harvey Keedwell. Her sisters were cookbook author Mary (later Browne) and watercolour artist Nancy (later Tichborne).

After moving with her family to Dunedin in the early 1950s, Leach and her sisters were educated at Otago Girls' High School. After joining the Otago Anthropological Society as a teenager, she went on to enrol at the University of Otago in 1963, from where she graduated Master of Arts.

Originally trained in archaeology, she completed a PhD in 1976 at Otago, with a thesis titled Horticulture in prehistoric New Zealand: an investigation of the function of the stone walls of Palliser Bay, with Charles Higham as her doctoral advisor. In the 1960's she was the first woman at the University of Otago to gain a Masters degree in anthropology, and also the first woman to obtain a PhD in anthropology.

Leach joined the staff of the University of Otago in 1972, and was appointed to a chair in anthropology in 2002.

Leach was renowned for her research into the origins of pavlova and Christmas cakes, writing several cook books touching the topic. Her work on the origins of the pavlova dessert, resulted in a book The Pavlova Story — A slice of New Zealand’s culinary history (2008). She also had an interest in prehistoric horticulture, human domestication, the evolution of the human diet, and the history of cooking and kitchens. Because of her interest in traditional Polynesian gardening practices, she was able to secure a Rhodes Visiting Fellowship, based at St Hilda's College from 1980–1981. She used this to study the role of kitchen gardening in New Zealand, leading her to write her next book 1,000 Years of Gardening in New Zealand (1984) and inspiring her next books that she wrote in the following years. Leach then lectured on human evolution before starting a new course at the University of Otago focussing on the evolution of the human diet in 1987.

With all of her academic achievements and affiliations, Leach was a member and supporter of many organisations, such as the Hocken Library, Royal Society of New Zealand (RSNZ), New Zealand Rhodes Scholar Association, New Zealand Federation of Graduate Women, Garden History Society, Otago Institute of Horticulture (RNZIH), and the Dunedin Botanic Gardens.

She studied food, eating, cooking, associated equipment and paraphernalia in New Zealand. Her interests ranged from prehistoric horticulture and the evolution of human diet to the history of cooking, the origins of recipes as well as the development of kitchens and batteries de cuisine in the twentieth century. Her extensive collection of over 2,000 cookery books, especially community cookbooks, provided a significant resource for colleagues' investigations, which compensated for the incompleteness of that in the National Library of New Zealand. Reviewing Leach's 2014 book Kitchens, Barbara Santich observed that "New Zealanders are indeed fortunate to have Helen Leach as guide, guardian and safe-keeper of their gastronomic past", noting too that the work was illustrated with images of artefacts from Leach's own personal collection.