Newcastle was a constituency represented in the Irish House of Commons until its abolition in 1801.
Newcastle was enfranchised by James I. By the late eighteenth century it had 13 electors, all non-resident. The patronage of the borough was sold by Lord Lanesborough to David La Touche in the between 1776 and 1779, allegedly for ã7,000. The borough was disfranchised by the Acts of Union 1800, with effect from 1 January 1801, with ã15,000 compensation paid under the will of David La Touche.