Martin Delrio was born in Antwerp on 17 May 1551, Whit Sunday, to the Spanish merchant Antonio del Río (d. 17 February 1586) and his wife Eleonora López de Villanova (d.
With the onset of the Dutch Revolt members of the family found employment with the Council of Troubles, the repressive institution set up by the new governor-general Fernando Álvarez de Toledo, 3rd Duke of Alba.