Niccolò Caetani (1526–1585) was an Italian Roman Catholic cardinal and bishop.
Niccolò Caetani was born in Rome on February 23, 1526, the son of Camillo Caetani, 3rd duke of Sermoneta, a cousin of Pope Paul III, and his second wife, Flaminia Savelli. His families were patricians from Naples. He was the uncle of Cardinal Enrico Caetani.
At the age of 10, Pope Paul III made him a cardinal deacon in pectore in the consistory of December 22, 1536. On March 5, 1537, he became administrator of the Diocese of Bisignano. His elevation to the cardinalate was published in the consistory of March 13, 1538; he received the red hat and the deaconry of San Nicola in Carcere on April 16, 1538.
On August 8, 1539, he was elected Bishop of Conza. He was promoted to the metropolitan see of Capua on May 5, 1546. He resigned the administration of Bisignano on March 13, 1549.
He participated in the papal conclave of 1549-50 that elected Pope Julius III.
He became administrator of the see of Quimper on July 14, 1550. On March 9, 1552, he opted for the deaconry of Sant'Eustachio.