The Plunkett family of county Louth was descended from Sir Hugh de Plunkett, an Anglo-Norman who came to Ireland during the reign of Henry II. From the fourteenth century they lived at Bewley near Drogheda , and a branch of the family was associated with Tallanstown by the late fifteenth century.

Sir John's son Oliver Plunkett was created Baron of Louth by Henry VIII on 15 June1541. By this time the Plunketts owned a tower house at Tallanstown, later called Louth Hall. It was there that the Lords Louth were to live for the next four hundred years. The 3rd Baron Louth, Patrick Plunkett, was killed in 1578 in county Monaghan while trying to recover cattle that had been stolen from him.

During the Elizabethan conquest the Plunketts remained loyal to the English Crown. But they also formed connections with the old Gaelic culture; in the seventeenth century they were closely allied with the MacDonnells of Antrim and the O'Neills of Clandeboye. But as the Plunkett estate had always been within the Pale, in a region dominated by the ‘Old English', they did not become Gaelicised. The Plunketts adhered to the Catholic faith through the 16th and 17th centuries. St Oliver Plunkett, the Catholic Archbishop of Armagh and primate of Ireland , who was put to death in London for high treason in1681, was closely related to the Plunketts. In the mid seventeenth century Lord Louth supported Oliver Plunkett and provided lodgings for him on his return to Ireland from Rome in 1670.

Though the Plunketts were deeply involved in the upheavals of the 1640s and 1689-91, they survived with their lands intact. During the rebellion of 1641, the 6th Baron Louth, Oliver Plunkett, together with several other Catholic Old English lords of the Pale, formed an alliance with Irish rebel leaders from Ulster. The Catholic gentry of Louth appointed Lord Louth as colonel-general of the royalist forces to be raised in the county, though he declined the position. He was taken prisoner in 1642 and outlawed for high treason. Under the Cromwellian land settlement, his lands were forfeited. When Charles II returned to the throne in 1660, most of these lands were restored to Lord Louth and to his son Matthew.

The accession of James II gave new life to Catholic aspirations. Matthew, the 7 th Baron Louth, joined the Jacobite cause in 1689 and commanded an infantry regiment at the siege of Derry . He was outlawed and exiled, and died in September 1689. Thomas, his second son, who had been sent to France for his education, returned and took part in the Jacobite campaigns, and was at Derry, the Boyne, Limerick, Aughrim and again at Limerick for the surrender, after which he sailed with Sarsfield for the continent. He had been indicted and outlawed after the Battle of the Boyne , and after the war ended he was indicted for high treason committed ‘in parts beyond the sea'.

The 8th Baron Louth, Oliver, was only twenty-one when he succeeded to the title in1689. Like his brother, he joined the Jacobite forces and was outlawed, and was in Limerick at the surrender in 1691. He was pardoned under the Articles of Limerick. But he was prevented from taking his seat in the House of Lords on the grounds that he had not proved the reversal of his grandfather's outlawry for rebellion in 1641. Eventually, the question was resolved and he was summoned to the House of Lords. In October 1695 Lord Louth took the oath of fidelity. But he refused to take both the oath of royal supremacy over the church and a declaration against Catholic religious practices and beliefs, and was ordered to withdraw. Attitudes towards Catholics hardened from the late 1690s under the Popery Acts, and it was another hundred years before a holder of the Louth title was permitted to sit in the House of Lords.

During the period of the Penal Laws, life was made hard for landowning Catholics. Like several other Catholic landowners in county Louth , the Plunketts changed their religion in the early 1700s. Matthew, the 9th Baron Louth (1698-1754), was a minor when his father Oliver died in November 1707. Eighteen months later he was brought to England and converted to Protestantism. Matthew remained a Protestant and his descendents were members of the Church of Ireland for many generations. But in the nineteenth century the family returned to the Catholic faith and Randal Percy Otway, the 13th Baron, was received into the Catholic Church on 6 December 1867.

St. Oliver Plunkett was a member of this family.

Joseph Mary Plunkett, who signed the Easter Proclamation in 1916, was a member of this family.