Nancy Helen Marcus (May 17, 1950 – February 12, 2018) was an American biologist and oceanographer. During her graduate studies, Marcus became known as an expert on copepod ecology and evolutionary biology. She began her career as a postdoctoral fellow at the Woods Hole Oceanographic Institution where she studied copepod dormancy and its implications for marine aquaculture. She continued her field research as a professor of oceanography and later as the director of the Florida State University Marine Laboratory (FSU). During this time Marcus was elected as a Fellow of the Association for Women in Science and the American Association for the Advancement of Science and served as the President of the Association for the Sciences of Limnology and Oceanography. As the president, she led efforts