Daniel Basil O'Connor was an American lawyer and nonprofit executive. In cooperation with U.S. President Franklin D. Roosevelt he started two foundations for the rehabilitation of polio patients and the research on polio prevention and treatment. From 1944 to 1949 he was chairman and president of the American Red Cross and from 1945 to 1950 he was chairman of the League of Red Cross Societies.

Franklin D. Roosevelt, later the 32nd president of the United States from 1933 to 1945, began experiencing symptoms of a paralytic illness in 1921 when he was 39 years old. His main symptoms were fevers; symmetric, ascending paralysis; facial paralysis; bowel and bladder dysfunction; numbness and hyperesthesia; and a descending pattern of recovery. He was diagnosed with poliomyelitis and underwent years of therapy, including hydrotherapy at Warm Springs, Georgia. Roosevelt remained paralyzed from the waist down and relied on a wheelchair and leg braces for mobility, which he took efforts to conceal in public. In 1938, he founded the National Foundation for Infantile Paralysis, leading to the development of polio vaccines. Although historical accounts continue to refer to Roosevelt's case as polio, the diagnosis has been questioned in the context of modern medical science, with a competing diagnosis of Guillain–Barré syndrome proposed by some authors.