Thomas Dongan, 2nd Earl of Limerick[a] (1634 – 14 December 1715) was an Irish military officer and colonial administrator who served as the governor of New York from 1683 to 1688.

Dongan was born in 1634 into an old Gaelic Norman (Irish Catholic) family in Castletown Kildrought (now Celbridge), County Kildare, in the Kingdom of Ireland, the seventh and youngest son of Sir John Dongan, 2nd Baronet, Member of the Irish Parliament, and his wife Mary Talbot, daughter of Sir William Talbot, 1st Baronet, and Alison Netterville.

After the beheading of Charles I, Dongan's father, a supporter of the House of Stuart, and his family, fled to France, where Thomas obtained a commission in the French Royal Army.

[3] After the Treaty of Nijmegen ended the Franco-Dutch War in 1678, Dongan returned to England in obedience to the order that recalled all English subjects in French military service.

Fellow officer James, Duke of York, arranged to have him granted a high-ranking commission in the English Army force designated for service in Flanders and a pension.

In September 1682, James, Duke of York, as Lord Proprietor of the Province of New York, appointed Dongan as vice-admiral in the Royal Navy and governor to replace Edmund Andros[6] "Dongan's long service in the French army had made him conversant with the French character and diplomacy and his campaigns in the Low Countries had given him a knowledge of the Dutch language.

[8][9] It decreed that the supreme legislative power under the Duke of York shall reside in a governor, council, and the people convened in general assembly; conferred upon the members of the assembly rights and privileges making them a body coequal to and independent of the Parliament of England; established town, county, and general courts of justice; solemnly proclaimed the right of religious liberty; and passed acts enunciating certain constitutional liberties, e.g. taxes could be levied only by the people met in general assembly; right of suffrage; and no martial law or quartering of the soldiers without the consent of the inhabitants.

[11] Dongan established the boundary lines of the province by settling disputes with Connecticut on the East, with the French Governor of Canada on the North, and with Pennsylvania on the South, thus marking out the present limits of New York State.

"[1] Dongan, along with Lord Howard of Effingham, Governor of Virginia, journeyed to the Iroquois nation around Albany in 1684, and convened assembly with them, garnering support, and approval.

[15] Dongan was to execute land grants establishing several towns throughout New York State including the eastern Long Island communities of East Hampton and Southampton.

In his will, dated 1713, he wished that he be buried with expenses not to exceed £100, and bequeathed the remainder of his estate to his niece, the wife of Colonel Nugent, who later became Marshal of France.