Swedish soldier from Stockholm who served in the private army of the Verenigde Oostindische Compagnie (Dutch East India Company). He was based at the Cape during the first voyage of James Cook and met J. Banks and D.C. Solander (1771), later sending South African specimens to Joseph Banks. Oldenburg also collected with C.P. Thunberg (1772). He acted as interpreter (1772-1773) for Francis Masson, the first professional plant collector to be sent out by the Royal Gardens at Kew, who arrived in South Africa as a passenger on HMS Resolution during the start of Cook's second voyage. He was later employed as a surgeon's mate during a voyage of the Hoeker to Madagascar, on the recommendation of Thunberg, but caught a fever and died. He is commemorated by Oldenburgia Less. in the Asteraceae.