Thomas Ronald Garnett OAM (1 January 1915 – 22 September 2006) was an English and Australian headmaster, horticulturist, ornithologist and author.

[1] Garnett was born at Marple, Cheshire and educated at Charterhouse School at Godalming, Surrey, and studied classics at Magdalene College, Cambridge.

He was the headmaster when Prince Charles spent two terms at Geelong Grammar School.

As secretary he bore the brunt of the administrative load of a body undergoing major change as it evolved from what had become largely a birdwatching club into a scientific conservation organisation undertaking ventures such as the Atlas of Australian Birds project.

[4] From 1980 Garnett devoted himself to developing the Garden of St Erth at Blackwood, Victoria, emphasising the use of Australian native plants in horticulture.