The Earldom of Castle Stewart was created in 1801 for the 9th Baron Castle Stuart who became 1st Viscount Castle Stuart in 1793 and 1st Earl Castle Stuart in 1800. The Earl was related to the Marquess of Londonderry, another Irish peer. Lord Castle Stewart was descended from Lord Ochiltree, an illegitimate scion of the Stewart kings of Scotland.

Earls Castle Stewart (1801)