McGregor, James (1677?–1729), presbyterian minister and emigrants' leader, was born in Magilligan, Co. Londonderry, one of two known sons of Capt. McGregor, who also had at least one daughter; nothing is known of his mother. During the Williamite war the family took refuge in Derry city, and James is said to have fired the gun announcing the approach of the relieving ships. He was well educated, and probably graduated from Glasgow University. He preached for a time in Macosquin, but declined a call from that congregation and was ordained as minister in Aghadowey 25 August 1701. McGregor was a fluent Irish-speaker, and was one of the ministers authorised by the synod of 1710 to travel among the native Irish for at least three months each year to preach in Irish. Though the ambitious plan seems not to have been carried out, McGregor is known to have preached before Irish-speaking congregations in several counties, and in 1716 he was instructed by the presbytery to preach a sermon in Irish to a society of ministers who were to meet regularly to improve their command of the language. In May 1704 a scandalous ‘flying report’ alleged that the minister had been drunk in Coleraine; a special presbytery met, and accepted McGregor's statement that he had not been drunk, but had had several cans of ale, and that ‘less might have serv'd’. He was exhorted to greater circumspection. In October 1706 he married Marion or Mary Ann Cargill, daughter of Aghadowey's elder David Cargill; her sister was married to a prominent merchant in Ballymoney, James McKeen, who was later a leader with McGregor of the emigration from the Bann valley to New Hampshire. Some sources state that McGregor's wife died in 1714, having had two children, and that he later married a daughter of James McKeen.
Economic conditions, as well as a perception among presbyterians that their religious freedom was under threat in Ireland, led to a decision to seek opportunities in America. In March 1718 over 300 presbyterians signed a petition to the colonial government. This was taken to America by the Rev. William Boyd (qv); but, without waiting for a response, McGregor and McKeen, with others, organised the emigration of several hundred people from the Bann valley in several small ships, which sailed from Coleraine and Belfast. They reached the port of Boston in August 1718; Boyd had arrived in late July, but had not managed to secure any land for the settlers. McGregor and an Archibald Boyd presented on 31 October 1718 a petition to the Massachusetts house of representatives, but though land was granted it was not surveyed until the following spring. Some of the settlers remained on the ship they had chartered, and spent a wretched winter frozen in sea ice at Casco Bay; McGregor was recommended by Cotton Mather, Boston's most influential clergyman, to the people of Dracut as their minister and teacher, and he passed the winter with them. In the spring of 1719 the scattered Ulster emigrants regrouped, and selected a tract of land near Haverhill; McGregor, whose commanding presence is frequently noted, preached from beneath an oak tree, an inspiring sermon to inaugurate a settlement first called Nutfield, and later Londonderry, New Hampshire. McGregor became their minister, the first presbyterian minister in New England, and was prominent in local affairs; he carried a loaded gun always, even into the pulpit, for fear of attack by Indigenous peoples, though it is said that his friendship with Philippe, marquis de Vaudreuil, governor of Canada, ensured that the community received some protection from the natives. A meetinghouse was built in 1722.
McGregor died of fever in New Hampshire on 5 March 1729; seven of his ten children survived him, along with his widow, who married his successor in the congregation, Matthew Clerk (qv) from Kilrea. McGregor's son David, the eldest son to survive to adulthood, became a presbyterian minister in New Hampshire, and was more renowned there than his father.