The Diocese of Frascati (Lat.: Tusculana) is a suburbicarian see of the Holy Roman Church and a diocese of the Catholic Church in Italy, based at Frascati, near Rome. The bishop of Frascati is a Cardinal Bishop; from the Latin name of the area, the bishop has also been called Bishop of Tusculum. Tusculum was destroyed in 1191. The bishopric moved from Tusculum to Frascati, a nearby town which is first mentioned in the pontificate of Pope Leo IV. Until 1962, the Cardinal-Bishop was concurrently the diocesan bishop of the see in addition to any curial duties he possessed. Pope John XXIII removed the Cardinal Bishops from any actual responsibility in their suburbicarian dioceses, and made the title purely honorific.
Like other dioceses close to Rome, Frascati became a bishopric of choice for Cardinals of powerful papal families during the 17th century; a period known for its unabashed nepotism. Frascati Bishops of that era were significantly intertwined:
Odoardo Farnese (1624–1626) - uncle of Odoardo Farnese, Duke of Parma against whom the Barberini fought the First War of Castro.
Bonifazio Bevilacqua Aldobrandini (1626–1627) - adopted "nephew" of Aldobrandini family Pope Clement VIII whose grand-niece Olimpia Aldobrandini married Camillo Pamphili, nephew of Pope Innocent X.
Marcello Lante della Rovere (1629–1639) - previous Bishop of Palestrina (the comune owned by the Barberini) uncle of Ippolito Lante Montefeltro della Rovere who was a close friend and counsel to Maffeo Barberini.
Giulio Cesare Sacchetti (1652–1655) - twice nominated for the papacy by Antonio Barberini.
Antonio Barberini (1655–1661) - nephew of Pope Urban VIII, brother of Taddeo Barberini (Prince of Palestrina), exiled by Pope Innocent X, later helped engineer the marriage of his nephew Don Maffeo Barberini to the grand-niece of Pope Innocent X.
Girolamo Colonna (1661–1666) - brother of Anna Colonna (wife of Taddeo Barberini, nephew of Pope Urban VIII), uncle of Don Maffeo Barberini and brother-in-law of Antonio Barberini.
Carlo Rossetti (1676–1680) - prelate to Pope Urban VIII and Antonio Barberini, supporter of Giulio Cesare Sacchetti
Sisinnius (732)
Nicetas (743-745)
Pietro (761)
Giorgio (826)
Pietro (853-869)
Leo (879)
Lunisso (963-968)
Benedetto (998-999)
Leo (?) (1004)
Johannes Homo (1015)
Domenico (1024–1036)
Giovanni (1044)
Pietro (before 1057 - after 1062)
Giovanni (1065–1071)
Giovanni Minuto (1073–1094)
Bovo (1099)
Giovanni 'Marsicano' (1100–1119)
Divizzo (Divitius, Denys, Dionysius, Divizo, Denigo) (1121–1122)
Gilles of Paris (1123–1139)
Imar (or Icmar), Benedictine (1142–1161)Teobaldo (1162), pseudocardinal
Ugo Pierleoni (1166)
Martino (or Marino) (1167-1174/78), pseudocardinal
Odon de Soissons (1170–1171)
Pietro da Pavia (1179 — 1182)
Serafino Vannutelli (1893–1903)
Francesco di Paola Satolli (1903–1910)
Francesco di Paola Cassetta (1911–1919)
Giulio Boschi (1919–1920)
Giovanni Cagliero, Salesiani di Don Bosco (1920–1926)
Michele Lega (1926–1935)
Francesco Marchetti Selvaggiani (1936–1951)
Federico Tedeschini (1951–1959)
Gaetano Cicognani (1959–1962)
Amleto Giovanni Cicognani (1962–1973)
Jean-Marie Villot (1974–1979)
Paolo Bertoli (1979–2001)
Alfonso López Trujillo (2001–2008)
Tarcisio Bertone (2008-)
Biagio Budelacci (-1962)
Luigi Liverzani (1962–1989)
Giuseppe Matarrese (1989–2009)
Raffaello Martinelli (since 2009)
Marco Antonio Bottoni, T.O.R. (1655-?)
Biagio Budelacci (1936-1962)
Francesco Giacci (1900-1904)
Edward Henry Howard (1872-?)
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