Samuel Gamble McFarland (December 11, 1830 – April 26, 1897) was an American Presbyterian missionary who worked mainly in Siam (Thailand) during the latter half of the 19th century. He and his wife settled in Phetchaburi, establishing churches and a school there, and he later came into the service of the government of King Chulalongkorn (Rama V) in Bangkok, heading the Suan Anan School (one of the earliest government schools aimed at educating sons of the nobility) from 1879 until its closure in 1892, after which he wrote Thai textbooks for the Department of Education. He most notably compiled an English–Thai dictionary which became the first widely used dictionary for Thai learners of English.