David Cosgrove was born in Moville, Co Donegal, Ireland on 17 February 1884. Hailing from a Roman Catholic family, he was the son of Naval seaman and coastguard Patrick Cosgrove and the former Johanna O’Dwyer, both natives of Co Cork who became parents to eleven children after their marriage in the early 1870s. 

By 1901 the Cosgrove family lived in Scartlea, Co Cork and David, aged 16, was described as a scholar; by 1911 that was still the family home but David was not listed, presumably being at sea at the time.

Between 1906 and 1912 Cosgrove was recorded as serving as a waiter aboard Carmania. In April 1912 he was serving as waiter aboard the eastward-bound voyage of the Carpathia when that ship rescued the survivors of the Titanic. 

It appears that Cosgrove remained in New York following the Titanic disaster and he declared intention of US citizenship in July 1917, by which time he described himself as a “Captain’s waiter.” He lived with his wife Mary in Manhattan for many years before moving to Boonton, New Jersey where he died on 21 March 1954.