McCourt was born in New York City, the son of Irish parents Angela (née Sheehan) and Malachy McCourt. He is the last survivor of their seven offspring, following the death of his younger brother Alphonsus in 2016. McCourt was raised in Limerick, Ireland, and returned to the United States in 1952. He has four children: Siobhán, Malachy III, Conor, and Cormac, the latter two by his second wife, Diana. He also has a stepdaughter, Nina. He was portrayed by Peter Halpin in the film version of his brother's memoir Angela's Ashes. He is also one of the four founding members of the Manhattan Rugby Football Club in 1960. Malachy appears in Frank McCourt's memoirs.
