Earl of Cardigan is an English peerage title. It was created in 1661 for Thomas Brudenell, who had been previously created Baron Brudenell (1628) and was an English Baronet, Brudenell of Deen. In 1790 the title Baron Brudenell of Deene merged with the earldom. The titles were inherited by the second Marquess of Ailesbury in 1868; the two titles have remained united since.