Earl of Sefton was a title in the Peerage of Ireland created in 1771 for the 8th Viscount Molyneux. The Earls of Sefton held the subsidiary titles Viscount Molyneux, of Maryborough in the Queen's County (created 1628), in the Peerage of Ireland, and (from the 2nd Earl onwards) Baron Sefton, of Croxteth in the County Palatine of Lancaster (created 1831), in the Peerage of the United Kingdom. The Molyneux's powerful allegiances led to an acquisition of lands and wealth throughout the period 1100–1700 when the family were Lords of the manor at Sefton.