Earl of Cavan is a title in the Peerage of Ireland. It was created in 1647 for Charles Lambart, 2nd Baron Lambart. He was made Viscount Kilcoursie, in the King's County, at the same time, also in the Peerage of Ireland. Lord Cavan was the son of Oliver Lambart, who had been elevated to the Peerage of Ireland as Lord Lambart, Baron of Cavan in the County of Cavan, in 1618).
The 7th Earl of Cavan was a general during the Napoleonic Wars, he was succeeded by his grandson the 8th Earl. The 10th Earl was an army commander during the First World War and later a British Field Marshal and Chief of the Imperial General Staff. As he died without male issue, he was succeeded by his youngest brother the 11th Earl. When the 12th Earl died, the title passed to Roger Cavan Lambart, a descendant of the 7th Earl.