Nancy Ann Lynch (born January 19, 1948, Brooklyn) is a professor at the Massachusetts Institute of Technology. She is the NEC Professor of Software Science and Engineering in the EECS department and heads the Theory of Distributed Systems research group at MIT's Computer Science and Artificial Intelligence Laboratory.
She is the author of numerous research articles about distributed algorithms and impossibility results, and about formal modeling and validation of distributed systems (see, e.g., input/output automaton). She is the author of the graduate textbook "Distributed Algorithms". She is a member of the National Academy of Engineering, and an ACM Fellow.