Alfred Blalock (April 5, 1899 - September 15, 1964) was a 20th-century American innovator in the field of medical science most noted for his research on the medical condition of shock and the development of the Blalock-Taussig Shunt, surgical relief of the cyanosis from Tetralogy of Fallot—known commonly as the blue baby syndrome—with his assistant Vivien Thomas and pediatric cardiologist Helen Taussig.