Lynn Margulis was a American microbiologist who was distinguished professor in the Department of Geosciences at the University of Massachusetts, Amherst. She originated the endosymbiotic theory and was one of the pioneers, along with James Lovelock, of the Gaia Hypothesis. From 1977 to 1980, she chaired the Space Science Board Committee on Planetary Biology and Chemical Evolution.

Margulis obtained a BA from the University of Chicago (1957), an MS from the University of Wisconsin (1960), and PhD from the University of California, Berkeley. Her former husband was Carl Sagan.