William Kirk (1795 – 20 December 1870) was an Irish linen-mill entrepreneur and Member of the Parliament of the United Kingdom. He was elected, with the endorsement of the Tenant Right League, as an independent for constituency of Newry in 1852, and again in 1857. He stood down as a candidate for re-election in 1859. In 1865 he entered the arena as a Liberal candidate for Armagh, but he failed to win the seat. His final appearance on the political stage was in 1868, when, returning to Newry as a Liberal, he successfully contested his old seat. Despite failing health, he continued to attend parliament, and maintained his support for tenant rights and for "mixed" (Catholic, Protestant) education.