Peerage of Great Britain, holders of titles created in the Kingdom of Great Britain between 1707 and 1800
Peerage of Ireland, holders of Irish titles created by the Crown before 1920, until 1801 carrying a seat in the Irish House of Lords, some of whom later sat in the House of Lords at Westminster
Peerage of Scotland, holders of Scottish titles created before 1707, some of whom later sat in the House of Lords, all of them having a seat there from 1964 to 1999
Peerage of the United Kingdom, holders of most titles created since 1801 in the United Kingdom of Great Britain and Ireland (renamed United Kingdom of Great Britain and Northern Ireland after 1921)
Representative peers, holders of Scottish and Irish peerages who represented their peer-groups in the House of Lords at Westminster