John Fabriacus (Giovanni Fabriciaco in Italian) was a Byzantine magister militum per Venetiae in charge of the duchy of Venice in 742. Following the murder of the doge Orso Ipato in 737, the Exarch of Ravenna imposed administration by annual magistri militum on Venice who replaced the doge. John was the fifth and last of these officials.

John's rule was particularly harsh. He sided with Heraclea in its conflict with its neighbour and rival Equilium during a violent clash between the two towns. He was deposed, and then, following a Byzantine custom, blinded and, finally, exiled. The Exarch of Ravenna allowed the resumption of the dogeship and the popular assembly elected Teodato Ipato, who was the son of Orso Ipato (the first historical doge) and who had been a magister militum three years earlier.

Because administration by the magistri militum was a relatively short interruption of the dogeship, this period is often referred to as an interregnum.

• Samuele Romanin, Storia documentata di Venezia, Venezia, Pietro Naratovich tipografo editore, 1853.

v t e Doges of Venice
Byzantine period (697–737) Paolo Lucio Anafesto Marcello Tegalliano Orso Ipato
Regime of the magistri militum (738–742) Domenico Leoni Felice Cornicola Teodato Ipato Jovian Ceparius John Fabriacus
Ducal period (742–1148) 8th century Teodato Ipato* Galla Lupanio* Domenico Monegario* Maurizio Galbaio Giovanni Galbaio* 9th century Obelerio degli Antenori*† Agnello Participazio Giustiniano Participazio Giovanni I Participazio* Pietro Tradonico† Orso I Participazio Giovanni II Participazio♦ Pietro I Candiano‡ Pietro Tribuno 10th century Orso II Participazio Pietro II Candiano Pietro Participazio Pietro III Candiano Pietro IV Candiano† Pietro I Orseolo♦ Vitale Candiano♦ Tribuno Memmo Pietro II Orseolo 11th century Otto Orseolo* Pietro Centranico* Domenico Flabanico Domenico I Contarini Domenico Selvo* Vitale Faliero Vitale I Michiel 12th century Ordelafo Faliero Domenico Michiel Pietro Polani * deposed     † executed or assassinated     ‡ killed in battle     ♦ abdicated
Republican period (1148–1797) 12th century Domenico Morosini Vitale II Michiel Sebastiano Ziani Orio Mastropiero Enrico Dandolo 13th century Pietro Ziani Jacopo Tiepolo Marino Morosini Reniero Zeno Lorenzo Tiepolo Jacopo Contarini Giovanni Dandolo Pietro Gradenigo 14th century Marino Zorzi Giovanni Soranzo Francesco Dandolo Bartolomeo Gradenigo Andrea Dandolo Marino Faliero† Giovanni Gradenigo Giovanni Dolfin Lorenzo Celsi Marco Cornaro Andrea Contarini Michele Morosini Antonio Venier 15th century Michele Steno Tommaso Mocenigo Francesco Foscari* Pasquale Malipiero Cristoforo Moro Nicolò Tron Nicolò Marcello Pietro Mocenigo Andrea Vendramin Giovanni Mocenigo Marco Barbarigo Agostino Barbarigo 16th century Leonardo Loredan Antonio Grimani Andrea Gritti Pietro Lando Francesco Donato Marcantonio Trivisan Francesco Venier Lorenzo Priuli Girolamo Priuli Pietro Loredan Alvise I Mocenigo Sebastiano Venier Nicolò da Ponte Pasquale Cicogna Marino Grimani 17th century Leonardo Donato Marcantonio Memmo Giovanni Bembo Nicolò Donato Antonio Priuli Francesco Contarini Giovanni I Cornaro Nicolò Contarini Francesco Erizzo Francesco Molin Carlo Contarini Francesco Cornaro Bertuccio Valiero Giovanni Pesaro Domenico II Contarini Nicolò Sagredo Alvise Contarini Marcantonio Giustinian Francesco Morosini Silvestro Valiero Alvise II Mocenigo 18th century Giovanni II Cornaro Alvise III Mocenigo Carlo Ruzzini Alvise Pisani Pietro Grimani Francesco Loredan Marco Foscarini Alvise IV Mocenigo Paolo Renier Ludovico Manin* † Marino Faliero (1354–55) was convicted of treason, executed and condemned to damnatio memoriae * Francesco Foscari (1423–57) was forced to abdicate by the Council of Ten * Ludovico Manin (1789–97) was forced to abdicate by Napoleon leading to the Fall of the Republic of Venice