Andrew Thomas Gage FLS CIE (14 December 1871 – 21 January 1945) was a Scottish botanist and surgeon in the Indian Medical Service who worked at the Calcutta Botanical Garden.

He then studied medicine and joined the Indian Medical Service, going to India in 1898 and serving in the North-West Frontier.

He was then posted curator to the herbarium of the Royal Botanic Garden at Calcutta to succeed David Prain who moved to become director and in this position he made several collection expedition.

He was also involved in establishing cinchona cultivation and taught at the Medical College in Calcutta.

He worked on the manuscript by Benjamin Daydon Jackson to produce a History of the Linnean Society of London (1938)[3] which was further expanded upon by W.T.