Gillian Rose Langley (born 10 August 1952) is a British scientist and writer who specialises in alternatives to animal testing and animal rights. She was, from 1981 until 2009, the science director of the Dr Hadwen Trust for Humane Research, a medical research charity developing non-animal research techniques. She was an anti-vivisection member of the British government's Animal Procedures Committee for eight years, and has worked as a consultant on non-animal techniques for the European Commission, and for animal protection organizations in Europe and the United States. Between 2010 and 2016 she was a consultant for Humane Society International.