Mary Jaqueline "Jacky" Tyrwhitt (25 May 1905 – 21 February 1983) was a British town planner, journalist, editor and educator.
She was at the centre of the transnational network of theoreticians and practitioners who shaped the post-war Modern Movement in decentralized community design, residential architecture and social reform.
In the 1950s she was a professor at the University of Toronto, where she helped establish a graduate program in city and regional planning and then in 1955 moved to the Harvard Graduate School of Design in the Department of City Planning and Landscape Architecture, where she taught for many years until her retirement.