João de Loureiro (1717, Lisbon – 18 October 1791) was a Portuguese Jesuit missionary and botanist.
After receiving admission to the Jesuit Order, he served as a missionary in Goa, capital of Portuguese India (3 years) and Macau (4 years).
In 1742 he traveled to Cochinchina, remaining there for 35 years.
Here he worked as a mathematician and naturalist, acquiring knowledge on the properties and uses of native medicinal plants.
In 1777 he journeyed to Canton, returning to Lisbon four years later.In 1790 he published a work on flora of Cochinchina titled Flora Cochinchinensis.
João de Loureiro has numerous species "loureiroi" dedicated to him, mostly plants but also the dinosaur Draconyx loureiroi in honour of him being the first Portuguese palaeontologist.