Theatines, an order of regular clerks, founded at Rome in 1524 by Gaetano di Tiene (died in 1547; canonized by Clement X.), Bonifazio di Colle, Giovanni Pietro Caraffa (afterward Pope Paul IV.), and Paolo Consigliari. Gaetano and Bonifazio were the first who united to form a society of priests following the rules of apostolic life as set down in the New Testament; hence its members were popularly known as Cajetans (Gaetani). But the extension and establishment of the order were mainly due to Caraffa, who was archbishop of Chieti (Lat. Theate) when he was received by Gaetano as his associate, and thus gave the order its official name. It was approved in 1524 by Clement VII., under the designation of "regular clerks," the dress of the members being that of the secular clergy. Caraffa had been elected superior general. Their first residence on Monte Pincio was sacked by the Spaniards May 6, 1527, and Gaetano was subjected to the most cruel tortures to make him give up the riches he was thought to possess.

He soon after retired to Venice with his companions, and was chosen superior, and he and they displayed extraordinary charity during the plague and famine of 1528. They were afterward united with the congregation of Somascha, founded about this time in a town of that name near Bergamo by St. Girolamo Emiliano. The two congregations were separated on the elevation of Caraffa to the papal chair, May 23, 1555. In 1547 they had only two establishments, one at Venice and another at Naples. Through the influence of Paul IV. they spread rapidly, and soon possessed four provinces in Italy, one in Germany, one in Spain, two establishments in Poland, one in Portugal, and one in Goa, In France they had only the Parisian residence, which produced several remarkable men. They also founded missions in Tartary, Tiflis, and Cir-eassia. At the beginning of the present century the Theatines did not exist outside of Italy, where they had nine establishments. These were all suppressed in 1870. - There were also two communities of Theatine nuns (one a congregation of hermits), both founded by Ursula Benincasa, the one in 1583, the other in 1610. Neither had ever more than two establishments, and both are now extinct.