Cathleen Synge Morawetz (May 5, 1923 – August 8, 2017) was a Canadian-born American mathematician. Morawetz's research was mainly in the study of the partial differential equations governing fluid flow. She is Professor Emerita at the Courant Institute of Mathematical Sciences at the New York University, where she has also served as director from 1984 to 1988. She was born in Toronto, Canada.