Luigi Amat di San Filippo e Sorso (20 June 1796 – 30 March 1878) was the dean of the College of Cardinals during the last part of the record long reign of Pope Pius IX.

The issue of an ancient and noble Catalan Sardinian family,[1][2] he was the fifth child and fourth son of Giovanni, Marquess of San Filippo, and Eusebia, Baroness of Sorso.

From that point on, he rose rapidly, becoming a bishop just one year after his ordination and soon after a nuncio to the Sicilian kingdom (then separate from mainland Italy), and later to Spain.

He was expelled when the Papal States broke off diplomatic relations with Spain in 1835, but two years later Pope Gregory XVI elevated him to the rank of cardinal.

During most of Pius IX's reign Cardinal Amat held control of the police force in the Papal States: it has come to light that early in Pius's reign he sacked many policemen because of their political sympathies and was involved in many major political incidents as sympathy within the Papal States for a united Italy increased in the early 1860s.