Barbara McClintock was an American scientist and cytogeneticist who made groundbreaking discoveries in genetics. She is best known for her work on maize (corn) and the discovery of "jumping genes" or transposable elements, which revolutionized our understanding of genetic regulation and mutation. McClintock received the Nobel Prize in Physiology or Medicine in 1983 for her contributions to genetics. Her pioneering research has had a profound impact on the field, establishing her as one of the foremost scientists of the 20th century.