The Diocese of Termia or Diocese of Thermae or Diocese of Thermia (Latin: Dioecesis Thermiensis seu Firminiensis) was a Latin Catholic crusader bishopric located in the Cyclades archipelago in the Aegean Sea ]], which in 1600 was renamed but .
Established in 1330 as Diocese of Ceo, as part of the Venetian Duchy of Naxos, on island territory in the Cyclades with see on the island of KeaRenamed in 1600 as Diocese of Thermia after its new see when the bishopric moved to the island of KythnosSuppressed in 1650, after the Ottoman conquestIn 1933 it would be nominally restored as Titular Episcopal See of Cea(all Roman Rite)
Suffragan Bishops of CeoNicolò (? – ?)Pietro, Dominican Order (O.P.) (1350.11.17 – ?)Princivalle, Friars Minor (O.F.M.) (1370.05.29 – ?)Simone da Arezzo, O.F.M. (1376.06.16 – ?)Giorgio (? – ?)Francesco da Venezia, O.F.M. (1422.07.06 – ?)Francesco Barberi (1435? – death 1445?)Francesco, O.F.M. (1445.06.09 – 1453.04.30), later Bishop of Naxos (Greek island) (1453.04.30 – ?)Giovanni di Sicilia, O.F.M. (1454.11.29 – ?)Nicolò (? – ?)Pietro (? – ?)Gómez (1498.05.24 – ?)Giorgio Barozzi (? – ?)Giovanni Zotto (1520.02.06 – ?)Dionisio Zannettini, O.F.M. (1529.02.08 – 1538.12.11), later Bishop of Milopotamus (also in Greece; 1538.12.11 – 1555)Costantino Giustianiani, O.P. (1540.08.27 – death 1546)Giovanni de Gaona, Canons Regular of saint Augustine (C.R.S.A.) (1546.02.19 – ?)Giacomo Rocca (1550? – ?)Suffragan Bishops of TermiaMetropolitan: Archdiocese of Naxos
Petrus Pitarca, O.F.M. (26 Jun 1617 - 1622 Died)Cristóforo Chrisostome Carletti, O.F.M. (23 May 1622 - 1634 Resigned)Giacomo Della Rocca (25 Sep 1634 - 1644 Died)Giovanni Camponeschi, O.F.M. (19 Dec 1644 - 22 Jun 1654 Confirmed, Bishop of Mottola)It is today listed by the Catholic Church as a titular see.
Since the diocese's nominal restoration in 1933, under the name Cea, it has had the following incumbents, so far of the fitting Episcopal (lowest) rank, but is vacant since decades:
James Thomas O’Dowd (1948.05.22 – 1950.02.05)José Clemente Maurer, Redemptorists (C.SS.R.) (1950.03.01 – 1951.10.27), as Auxiliary Bishop of La Paz (Bolivia) (1950.03.01 – 1951.10.27), later Metropolitan Archbishop of Sucre (Bolivia) (1951.10.27 – 1983.11.30), created Cardinal-Priest of SS. Redentore e S. Alfonso in Via Merulana (1967.06.29 – 1990.06.27), President of Episcopal Conference of Bolivia (1968 – 1979)Father Wesceslau Nazareno Ponte de Spoleto, Capuchin Friars (O.F.M. Cap.) (1952.04.26 – 1952.06.29)Lawrence Bernard Brennan Casey (1953.02.10 – 1966.03.04). 