Dr. Sarah Mary Liao Sau-tung, GBS, MBE, JP, FRSC (born 25 December 1951) was former Secretary for the Environment, Transport and Works of the Hong Kong Special Administrative Region and a member of the Executive Council of Hong Kong since 2002. She was appointed on 1 August 2002 and served until 2007. She is also a Senior Adviser to the Vice-Chancellor of the University of Hong Kong on Environmental and Sustainability Matters.