Matthew Derbyshire Mann (July 12, 1845 – March 2, 1921) was an American gynecologist and one of the surgeons who operated on President William McKinley after he was shot on the grounds of the Pan-American Exposition on September 6, 1901, in Buffalo, New York, by anarchist Leon Czolgosz.

He graduated from the Columbia University College of Physicians and Surgeons in 1871 with a Doctor of Medicine.

[1] In 1894, Mann began working as a consulting gynecologist and obstetrician at the Buffalo General Hospital.

Mann operated on President William McKinley after he was shot on the grounds of the Pan-American Exposition on September 6, 1901.

They had seven children, Ethel, Edward Cox, Arthur S., Paul F., Matthew D. Jr., Alan N. and Richard[1][4] They lived on Allen Street in Buffalo.