Robert John Lechmere Guppy (15 August 1836 in London – 5 August 1916 in San Fernando, Trinidad and Tobago) was a British-born naturalist after whom the guppy is named. He was one of four children of Robert Guppy, a lawyer and the Mayor of San Fernando (Trinidad), and Amelia Parkinson, a painter and one of the pioneers of photography, who navigated the Orinoco River accompanied by only a few native Indians. "Lechmere", as he was called, was raised by his grandparents, Richard Parkinson and Lucy Lechmere, in Kinnersley Castle, a 13th-century Norman castle in Herefordshire. Richard Parkinson wanted Lechmere to take over the castle, a role in which he had no interest. Having come into an inheritance from another relative, he left England at the age of 18 and was shipwrecked on the coast of New Zealand in 1856. After living with the Māoris for two years and mapping the area, Lechmere left New Zealand for Trinidad, where his parents were living. He married Alice Rostant, the daughter of local French creole planters and a descendant of the Counts of Rostant, French aristocrats who had fled to Trinidad to escape the French Revolution and became Trinidad's first Superintendent of Schools. Although he had no formal training in the sciences, (he was a civil engineer by trade), Lechmere wrote and published numerous articles on the palaeontology of the region. Though sometimes rumored to have been a clergyman, Robert Guppy was in fact an agnostic.
Guppy discovered the Guppy fish in Trinidad in 1866, and the fish was named Girardinus guppii in his honour by Albert C. L. G. Günther later that year. However, the fish had previously been described in America. Although Girardinus guppii is now considered a junior synonym of Poecilia reticulata, the common name "guppy" still remains.
Guppy, R. J. Lechmere; Hogg, Jabez (1868). "IV. On the Lingual Dentition of some West-Indian Gasteropoda.". Transactions of the Linnean Society of London26: 191. doi:10.1111/j.1096-3642.1968.tb00505.x.
Lechmere Guppy, R. J. (1911). "On the Geology of Antigua and other West Indian Islands with reference to the Physical History of the Caribean Region". Quarterly Journal of the Geological Society67: 681. doi:10.1144/GSL.JGS.1911.067.01-04.26.
1912. "Fossils from Springvale near Couva, Trinidad". Agricultural Society of Trinidad and Tobago, 2: London.