Sir Proby Thomas Cautley (1802 - January 25, 1871), English engineer and palaeontologist, was born in Suffolk.

After some years service in the Bengal artillery, which he joined in 1819, he was engaged on the reconstruction of the Doab canal, of which, after it was opened, he had charge for twelve years (183 11843). In 1840 he reported on the proposed Ganges canal, for the irrigation of the country between the rivers Ganges, Hindan and Jumna, which was his most important work. This project was sanctioned in 1841, but the work was not begun till 1843, and even then Cautley found himself hampered in its execution by the opposition of Lord Ellenborough.

From 1845 to 1848 he was absent in England owing to ill-health, and on his return to India he was appointed director of canals in the North-Western Provinces. After the Ganges canal was opened in 1854 he went back to England, where he was made KCB, and from 1858 to 1868 he occupied a seat on the council of India. He died at Sydenham, near London, on the 25th of January 1871.

In 1860 he published a full account of the making of the Ganges canal, and he also contributed numerous memoirs, some written in collaboration with Dr Hugh Falconer, to the Proceedings of the Bengal Asiatic Society and the Geological Society of London on the geology and fossil remains of the Sivalik Hills.