Williams, Daniel (1643/4–1717), nonconformist minister and benefactor, was born in or near Wrexham, Denbighshire, north Wales. His father's name is not recorded, but his mother may have been a daughter of Hugh Davies of Wrexham, and there was at least one sister who married a local landowner. He did not attend any university, but had become a presbyterian minister by the time he was 19, despite the persecution experienced by nonconformists after the act of uniformity of 1662, and in about 1664 he moved to Dublin as chaplain to Mary Brabazon (née Chambre), a woman from Denbigh who was married to the 1st earl of Meath. He also preached to a congregation of independents in Drogheda, and in 1667 was called by the congregation of Wood St., Dublin, where his opinions became more strongly presbyterian, and where he was the colleague of Joseph Boyse (qv). He married (in or after October 1675) Elizabeth Juxon, a widow with children, daughter of Sir Robert Meredyth of Greenhills, Co. Kildare, son of Richard Meredith (qv), a clergyman from Wales; her sister Alice was married to the 2nd earl of Mountrath and was mother of Charles Coote (qv) (d. 1709). Elizabeth Williams was well connected and very wealthy; she died in 1698, without having had any more children, and leaving a fortune to her husband. During the reign of James II (qv) Williams, feeling his life was in danger, fled to London, where he convinced his fellow dissenters not to thank the king for his apparently gracious offer of liberty of conscience; Williams argued that many liberties were at risk if a monarch could arbitrarily grant or withhold them. In 1687 he became minister of Hand Alley, Bishopsgate, where he remained for the rest of his life.
When William III (qv) became king, Williams advised him on matters relating to Irish dissent, and greatly assisted many Irish refugees and others who sought redress at court. He was probably the most prominent dissenting minister in London, and led delegations to welcome the accession of Queen Anne and of George I. He was, however, involved in several theological controversies and was author of a number of works to counter antinomian tendencies in his contemporaries, as well as of many sermons and pamphlets. Gospel truth (1692) was probably his most important work, and was republished in 1740. He opposed without success the imposition of the sacramental test by the Irish parliament in 1704, but supported the union of parliaments of England and Scotland in 1707. He was awarded the degree of DD by both Glasgow and Edinburgh universities in 1709, though he had at first attempted to refuse the honour.
By his second marriage (1701) to Jane Barkstead, a widow whose father, George Guill, was a huguenot merchant, Williams gained more stepchildren and another large fortune. He died childless at Hoxton on 26 January 1717 and was buried in Bunhill Fields; his will, after confirming a settlement on his widow, disposed of almost £50,000 to benefit charitable and religious causes in three kingdoms, and he even willed money to support two preachers who were to travel among the Native Americans. Money was left in trust to provide for a minister in Ireland to preach in Irish, for Welsh charity schools and chapels, for the education of the poor in Dublin, and for paupers in Wood St., Dublin. Poor ministers and their widows were to receive help. Williams felt strongly that English and Welsh dissenting ministers should be educated at one of the Scottish universities, and left estates to the University of Glasgow in order to fund six studentships. Though many of Williams's legacies continue to be paid out to recipients, his name is best known for its association with the library founded on his instructions by trustees of his bequests. Dr Williams's library has become the most important nonconformist library in London, with fine collections of manuscripts and publications vital for historians of all the dissenting sects, and containing the personal library and portrait of the founder. Williams's will provided for the reversion of the properties that supported his bequests to the cities of Edinburgh and Glasgow, which are to fund almshouses, but only after the year 3717, and only if the protestant religion has not in the meantime been extinguished. The testator also directed that his writings were to be republished by his trustees at intervals for the coming 2,000 years.