Katherine MacLean (born January 22, 1925) is an American science fiction author. Employed as a biological laboratory technician, she began writing science fiction in the late 1940s. Her work has been principally short stories, often with a biological theme, and sometimes showing remarkable foresight. Examples:
- Syndrome Johnny, published in 1948, before it was even certain that DNA carried genetic information, is about a series of engineered retroviral plagues, initially propagated by blood transfusion, that are genetically re-engineering the human race
- The Diploids, from the 1950s, in which a young lawyer, who suspects that he may even be an alien because of certain physical and biochemical abnormalities, discovers that he is a commercial human embryonic cell line, sold for research, and illegally grown to maturity.
She was awarded the Nebula award in 1971 for her story The Missing Man, one of a series about a balkanised New York, in which an engineer working for the city's disaster planning section has his inside knowledge exploited to cause disasters.