Lieutenant-Colonel William Lambton, FRS (c. 1753 – 20 or 26 January 1823) was a British soldier, surveyor, and geographer who began a triangulation survey in 1800-1802 that was later called the Great Trigonometrical Survey of India. His initial survey was to measure the length of a degree of an arc of the meridian so as to establish the shape of the earth and support a larger scale trigonometrical survey across the width of the peninsula of India between Madras and Mangalore. After triangulating across the peninsula, he continued surveys northwards for more than twenty years. He died during the course of the surveys in central India and is buried at Hinganghat in Wardha district of Maharashtra. He was succeeded by his assistant George Everest.