Molyneux, Daniel (1568–1632), herald, was born in Bruges, Flanders, second son of Thomas Molyneux (qv) of Calais and his wife Katherine, daughter of Ludowick Slobert, burgomaster of Bruges. His father had been a member of the English community at Calais and had settled in Bruges after Calais fell to France in 1558. However, soon after Daniel's birth his family were effectively forced to leave Bruges for London, because of their protestant convictions, and then (1576) they settled in Dublin. Thomas prospered and became chancellor of the exchequer for Ireland but, due to his extravagant habits, left little for his sons to inherit.
Educated at Cambridge, Daniel was proficient in Greek. On 28 June 1597 he was appointed Ulster king of arms and principal herald of the kingdom of Ireland. This position, which was to occupy him for the rest of his life, involved certifying family pedigrees and dispensing heraldic emblems. Occasionally he would go on visitations to the country to investigate family histories. A collection of manuscripts detailing his research into Irish family history can be found in TCD; they testify to his skill as an antiquarian. Genealogies were a particularly sensitive issue for most of Molyneux's contemporaries, who were very quick to take offence at perceived slights to their family's honour. In May 1605 Molyneux was attacked at his home in Thomas Court, Co. Dublin, by Sir William Steward, against whom he had ruled on a matter of precedence. Assisted by two servants, Steward severely wounded Molyneux and would surely have killed him, had Molyneux's cook not chased the assailants away with a red-hot spit.
However, for the most part Molyneux enjoyed a quiet life as a comfortable member of the newly formed protestant establishment, sitting as MP for Strabane in the 1613–15 Irish parliament, and as the recipient of a government pension, although he had difficulties in getting it paid during the 1620s. He spent the summer of 1612 in London, researching procedures for holding a parliament in Ireland. He died 13 June 1632. He married (date unknown) Jane, daughter of Sir William Ussher, clerk of the Irish privy council; they had five sons and three daughters.