Alexander Keith Johnston (December 28, 1804 - July 9, 1871) was a Scottish cartographer and map publisher active in the middle portion of the 19th century. Johnson was born at Kirkhill, near Edinburgh, Scotland. He studied at the University of Edinburgh where he apprenticed as an engraver. Around 1826, in partnership with his brother William, he founded a cartographic printing and engraving firm with the imprint "W. and A. K. Johnston." Johnston made a name for himself in educational geography, publishing numerous maps for use in schools. His brother, William Johnston, eventually left the firm to pursue a career in politics, eventually becoming the Lord Provost of Edinburgh. Alexander's son, who would bear the same name, became a geographer and explorer, suffering an untimely death on the Royal Geographical Society's 1879 expedition to Lake Nyasa.