Swift, Hewson Hoyt (1920-2004) was an American microbiologist. His research on cell biology and genetics contributed to the understanding of the structure of chromosomes and the function of DNA.

In Swift's early research, he used microphotometry and autoradiography to examine the role of nucleic acids in such biological processes as mitosis, growth, and differentiation. He later used an electron microscope to study nucleic acids of mitochondria (the organelles outside a cell's nucleus that produce energy for the cell through cellular respiration) and chloroplasts (the organelles in plants that contain chlorophyll and perform photosynthesis).

In 1950, Swift investigated the molecular arrangement of chromosomes to determine the amount of DNA per nucleus in plant tissues. It had already been found in studies on animal tissues that all animal cells contain the same amount of DNA. Swift's research demonstrated that the same held with plant cells. He also studied the characteristics of membrane proteins in primitive marine algae, DNA-scaffold attachments in human lymphocytes, and a gene that affects cell shape in a bacterium.

Swift earned a B.A. degree from Swarthmore College in Pennsylvania in 1942. In 1945, he earned an M.S. degree from the University of Iowa and worked in Washington, D.C., as an entomologist for the U.S. Department of Agriculture and then as curator of spiders at the U.S. National Museum. He received a Ph.D. degree in zoology in 1950 from Columbia University, New York. In 1949, he became a lecturer in zoology at the University of Chicago, assistant professor in 1951, and full professor in 1971. From 1972 to 1977, he was Distinguished Service Professor of Biology and Pathology and chairman of the biology department. He was the George Wells Beadle Distinguished Service Professor of Molecular Genetics and Cell Biology from 1977 to 1990. In 1960, with Keith Porter, he cofounded the American Society for Cell Biology, serving as its president from 1963 to 1964. From 1976 to 1979, he chaired the cellular and developmental biology department at the National Academy of Sciences.