John Glendy (1755 – 1832) was a Presbyterian clergyman from County Londonderry in Ireland, who, after being forced into American exile for his association with the United Irishmen, found favour with President Thomas Jefferson and became a leading cleric in Baltimore.

On his return, Frederick Hervey, the Earl Lord Bishop at Londonderry was so impressed with the young graduate that he offered to take him along as a chaplain on a tour of Europe.

[5] When, with the further inspiration of the French Revolution, the volunteer movement revived in the early 1790s, Glendy regularly advanced theological justifications for a programme of Catholic emancipation and democratic reform.

Glendy was denounced in print by James Spottswood, agent in Magherafelt for the Salters Company of London (original Plantation undertakers and landowners).

There is an account that places Glendy on June 8 in a "council of war" with Graham, the county's United Irish commander William McKeever (a Roman Catholic), and Thomas Clarke from Swatragh (deciding on what they hoped would be a covered withdrawal).

[13] In 1803, he then went on, with Thomas Jefferson's recommendation, and over the objection of Federalist sympathisers, to be pastor of the Second Presbyterian Church in Baltimore (a favoured destination for Ulster emigrants).

They included the physician, John Campbell White, a United Irish exile from Templepatrick, County Antrim who was to play a leading role in the defence of Baltimore against the British in 1812.

[13] Jefferson’s influence likely contributed to Glendy’s election as chaplain for the United States House of Representatives for the first session of the Ninth Congress, on 4 December 1805.

His friend Samuel Miller at the Princeton Theological Seminary, also an anti-Federalist, was insistent that "every civil magistrate ought to be a christian, to love the church, and to seek to promote her interests.

"[13] On the occasion of a presbytery meeting in Washington, D.C., Glendy was described as "an elegantly dressed man ... his complexion pale, and his eyes a piercing blue", who being short of stature stood to orate on a large pulpit bible.

Doctor of divinity for upwards of twenty years minister of the congregation of Maghera Co Derry, and latterly of the city of Baltimore of the United States.

In the Country of his adoption, he was highly esteemed by all classes, and could number among his friends and admirers the late President Jefferson, with whom he became early acquainted and who, till the close of his life, uniformly treated him with kindness and attention.