Martha Ann Cassell Thompson (1925 -1968) was a member of the prominent Cassell Family of African-American architects. She was the chief restoration architect for the National Cathedral. She attained a bachelor of science in architecture from Cornell University's School of Architecture in 1948.

Thompson, from 1949-1951, worked for an architectural firm in St. Louis. After which, she worked with architect Philip Hurbert Frohman (1887-1972) at the firm Frohman, Robb, & Little in the District of Columbia. There, given her expertise on Gothic architecture, she became the chef restoration architect for the Cathedral of St. Peter and Paul (originally designed by Bodley & Vaughn), later known as the Washington National Cathedral. She was also one of the only women architects on the team responsible for the completion of the project. She worked on the project from 1959-1968.