Irish nobility refers to persons who fall into one or more of the following categories of nobility.
- Gaelic nobility of Ireland are those who qualified under the rules of tanistry, or otherwise were or are descendants in the male line of at least one historical grade of king (Rí). This group includes the descendants of the Norse-Gaelic kings as well. The article for this branch of nobility sets out the degrees of kingship and the trappings of kingship in Gaelic Ireland.
- Hiberno-Norman or Old English (Ireland) nobility who were the descendants of the settlers who came to Ireland from Wales, Normandy and England after the Norman invasion of Ireland in 1169–71.
- Peerage of Ireland who owe their titles to those created by the English and later British monarchs of Ireland in their capacity as Lord or King of Ireland.
These groups are not mutually exclusive. There is a high degree of overlap between groups 1 and 2 (prior to the Treaty of Limerick). There is a lesser degree of overlap between groups 2 and 3 (prior to the declaration of the Republic of Ireland). There is also a lesser degree of overlap between groups 1 and 3. Such overlaps may be personal (e.g. a Gaelic noble who was "regranted" his titles by King Henry VIII of England), or they may be geographical (i.e. different noble traditions co-existing in neighbouring parts of the country, which were only distinguished by the date when they were finally conquered by the Dublin administration).
From 1948 to 2003, the Republic of Ireland gave a form of courtesy recognition to the heirs of the Gaelic-era Chiefs of the Name, but they had no special legal or political status beyond recognition. They were listed as such by the Chief Herald of Ireland. The Republic of Ireland considers such inherited ranks of distinction to be irrelevant in modern Ireland. Article 40.2 of the Irish Constitution forbids the state conferring titles of nobility and citizens may not accept titles of nobility or honour except with the prior approval of the Government. However, noble titles are still used by people of noble descent in the Republic of Ireland. Noble titles are still used and awarded in Northern Ireland, which remains a part of the United Kingdom of Great Britain and Northern Ireland.
- "40.2" (PDF), Constitution of Ireland, Dublin: Stationery Office