Margaret Merrell (December 3, 1900 – 21, 1995) was an American biostatistician who taught at Johns Hopkins University for many years and became the first female full professor in the Johns Hopkins School of Public Health. She is known for her research with Lowell Reed on the construction of life tables. She also observed that, for longitudinal data on individuals, fitting a curve to each individual and then averaging the parameters describing the curve will typically give different results than averaging the data values of the individuals and fitting a single curve to the averaged data.