Peter Seton Hay (1852–19 March 1907) was a New Zealand civil engineer and public servant. He was born in Glasgow, Lanarkshire, Scotland on 12 July 1852. He was brought to Dunedin in April 1860. In 1875, he joined the Public Works Department, as an engineering cadet, and was awarded a University of Otago BA in 1877 and an MA in 1878. He married Mary Clarke on 22 April 1879 and was survived by her, four sons and a daughter.