Alexander Keith Johnston (1844, November 11 in Edinburgh – 1879, June 28 in Tanzania) was a Scottish explorer and geographer.
He was the son of Alexander Keith Johnston (1804-1871).
From 1873 to 1875 he was geographer to a commission for the survey of Paraguay; and he died in Africa while leading the Royal Geographical Society's expedition to Lake Nyasa.
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press