Thomas Horsfield M. D. (May 12, 1773 – July 24, 1859) was an American physician and naturalist.
Horsfield was born in Bethlehem, Pennsylvania, and studied medicine at the University of Pennsylvania.[1] He was the grandson of Timothy Horsfield, Sr., a colonel and justice of the peace in Bethlehem, and a friend mentioned in Benjamin Franklin's autobiography. The Horsfield family had converted to Moravianism, a Protestant denomination with a strong emphasis on education. In 1800 Thomas Horsfield travelled to Java for the first time and worked there as a doctor for many years. The East India Company took control of the island from the Dutch in 1811, and Horsfield began to collect plants and animals on behalf of his friend Sir Thomas Stamford Raffles. In 1819 he was forced to leave the island due to ill health and became keeper and later curator of the East India Company's museum in Leadenhall Street, London.
Horsfield wrote Zoological Researches in Java and the Neighbouring Islands (1824). He also classified a number of birds with Nicholas Aylward Vigors, most notably in their A description of the Australian birds in the collection of the Linnean Society; with an attempt at arranging them according to their natural affinities (Trans. Linn. Soc. Lond. (1827)). Together with the botanists Robert Brown and John Joseph Bennett he published the Plantae Javanicae rariores (1838–52).
Horsfield was appointed assistant secretary of the Zoological Society of London at its formation in 1826. In 1833, he was a founder of what became the Royal Entomological Society of London. He was elected a fellow of the Royal Society in 1828.
Horsfield died at his home in Camden Town and was buried at the Moravian cemetery in Chelsea.
Horsfield is commemorated in the names of a number of animals, including: