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.
One of her most famous stories is "The Snowball Effect", in which a sociology professor, challenged to prove his theories of the dynamic growth of organisations, rewrites the rules of a small-town sewing circle, to have "more growth drive than the Roman Empire". He is far more successful than he ever anticipated....
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.
She was the Professional Guest of Honor at the first WisCon.