Michael Thomas Gillies (15 September 1920 – 10 December 1999) was an English medical entomologist. He spent most of his working life in the tropics, particularly Tanzania (then known as Tanganyika) and later The Gambia, studying the transfer of malaria between mosquitos and humans. He was awarded the Chalmers and Sir Rickard Christophers Medals for his seminal contribution to the understanding of the role of mosquito behaviour in the transfer of malaria. He was also a world authority on the mayfly.