The Kingdom of Ireland (Irish: Ríoghacht Éireann) refers to the country of Ireland in the period between the proclamation of Henry VIII as King of Ireland by the Crown of Ireland Act 1542 and the Act of Union in 1800. It replaced the Lordship of Ireland, which had been created in 1171. King Henry VIII was recognised as monarch of Ireland by some Protestant powers in Europe, although not by the Catholic monarchies in Europe. However his daughter Mary I was recognised as Queen of Ireland by the pope in 1555. The separate Kingdom of Ireland ceased to exist when Ireland joined with the Kingdom of Great Britain to form the United Kingdom of Great Britain and Ireland in 1801.

The papal bull Laudabiliter of Pope Adrian IV was decreed in 1155. It granted the Angevin King Henry II of England who ruled from Anjou in France, the title Dominus Hibernae. Laudabiliter enabled the king to invade Ireland, in order to bring the country into the European sphere. In return, Henry was required to remit a penny per hearth of the tax roll to the Pope. This was reconfirmed by Adrian's successor Pope Alexander III in 1172.

Coordinates: 53°20′N 08°00′W / 53.333°N 8°W / 53.333; -8

Ireland (pronounced [ˈaɪrlənd] ( listen); Irish: Éire [ˈeːɾʲə] ( listen); Ulster Scots: Airlann or Airlan) is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth. To its east is the larger island of Great Britain, from which it is separated by the Irish Sea.

Politically, Ireland is divided between the Republic of Ireland, which covers just under five-sixths of the island, and Northern Ireland, a part of the United Kingdom, which covers the remainder and is located in the northeast of the island. The population of Ireland is approximately 6.4 million. Just under 4.6 million live in the Republic of Ireland and just under 1.8 million live in Northern Ireland.

Relatively low-lying mountains surrounding a central plain epitomise Ireland's geography with several navigable rivers extending inland. The island has lush vegetation, a product of its mild but changeable oceanic climate, which avoids extremes in temperature. Thick woodlands covered the island until the 17th century. Today, it is one of the most deforested areas in Europe. There are twenty-six extant mammal species native to Ireland.