John Campbell White (1757–1847) was an executive member of the Society of United Irishmen in 1798 as it prepared in Ireland for insurrection against the British Crown and Protestant-landed Ascendancy.

[1] It is possible with other Presbyterian ministers of his generation the elder White, either at an academy in Dublin or at the University of Glasgow, had studied with "the father of the Scottish Enlightenment", Francis Hutcheson.

[5][6] In the midst of early enthusiasm in Belfast for the revolutionary events in France and the revival of the Irish Volunteer movement, White's fellow Glasgow-trained physician, William Drennan, proposed to his friends "a benevolent conspiracy—a plot for the people", the "Rights of Man and [employing the phrase coined by Hutcheson] the Greatest Happiness of the Greater Number its end—its general end Real Independence to Ireland, and Republicanism its particular purpose.

During the War of 1812 he played a leading role in the defence of Baltimore against the British, serving as a member of the ‘committee of supply’ which had at its disposal $20,000 for defensive purposes.

The republican sympathies, both American and Irish, of the Society were made plain in a series of St Patrick’s day toasts following White's re-election a president in 1804: "Our Native Land", ‘Our Adopted Country", "Thomas Jefferson", "Lately Imported Patriots", "United States as Asylum for the Persecuted", "Civil and Religious Liberty to All Mankind", "Our Distressed Brethren in Ireland", and "Fair Daughters of Erin, may they never smile on the enemies of their country".

An obituary appearing in the Freeman's Journal in Dublin read, in part:As an ardent philanthropist and sincere patriot, whose aspirations were always directed to the best interests of mankind and the promotion of the freedom of his native land, his name is intimately associated with the political history of Belfast, during the eventful years of the Volunteers, and the subsequent period of excitement.

Nearly fifty years ago, Dr White, disgusted with the state of public affairs in Ireland, abandoned his professional prospects here, and emigrated to America, then in the early enjoyment of freedom, where he enjoyed a long career of prosperity and happiness, and with better fortune than many of his compatriots, survived the recognition of Great Britain, of those great measures of civil and religious liberty for which he had, in early life, unsuccessfully contended.