 Henry MacCormac married his distant cousin, Mary Newsam, the daughter of William Newsam, a wealthy linen merchant whose family went to Ireland in 1640.The MacCormac family had three sons and two daughters, including William MacCormac, who served as President of the Royal College of Physicians and was knighted by Queen Victoria.Through his youngest son, Henry MacCormac was also the great grandfather of Sir Richard MacCormac, a notable architect in the 20th and early 21st centuries.