Donald Flanders was an American mathematician who worked on the Manhattan Project at Los Alamos. Flanders was a group leader in the Theoretical Division headed by Hans Bethe. The T-5 group, which often employed the wives of Los Alamos scientists and workers, was given computations needed by other groups and used Marchant computers for their work. Physicist Roy Glauber, also a member of the Theoretical Division, remembered that Flanders was also very musical and served as the director of the singing groups at Los Alamos.