Gian Antonio Lazier (9 June 1678[a] – 8 April 1738), also known under his claimed official name Ioannes IX Antonius I Angelus Flavius Comnenus Lascaris Palaeologus, and various variations thereof, was an 18th-century Italian impostor and pretender.

Born of lowly origins in the Aosta Valley in Italy, Lazier claimed his last name to be a corruption of the surname Laskaris, an imperial dynasty of the Byzantine Empire.

Through various noble titles, Lazier claimed to be the rightful ruler of a vast number of former territories of the Byzantine Empire as well as of a selection of other eastern lands.

Sometimes nicknamed "the peasant who wanted to become emperor", Lazier spent several years of his early life travelling around Italy in search of work he found suitable.

From 1720 to his death in 1738, Lazier operated out of Vienna as if he were a pseudo-Byzantine emperor in control of an imperial government in exile, with his documents describing his imperium Romano-Byzantium as a present, albeit virtual and landless, entity rather than as something of the past.

Lazier's activities, which until 1725 were fully recognized and supported by the Holy Roman emperor Charles VI, helped revive interest in the Byzantine Empire in Western Europe and might also have led to a late and ephemeral surge in crusading sentiments.

[4][5] Thomas and his son Andreas Palaiologos, who later proclaimed himself emperor-in-exile, spent much of their lives unsuccessfully attempting to secure military aid from Western Europeans to retake their former empire.

[6][7] Andreas' death in poverty in June 1502 left the line of succession uncertain and the title of despot of the Morea was on unclear grounds claimed by the unrelated Constantine Arianiti, an Albanian nobleman and military leader.

[17] Andrea Angeli's claims were accepted in Western Europe without much dispute and he was officially acknowledged as a descendant of the Angelos dynasty by Pope Paul III (r. 1534–1549) and guaranteed the right to inherit territories in the former Byzantine Empire, should they be recovered from the Ottomans.

[19] The last male member of the Angelo Flavio Comneno family, Giovanni Andrea II Angeli, transferred the rights of the Constantinian Order in 1698 to the unrelated Francesco Farnese, the Duke of Parma, and his descendants.

[1] Also of concern to Charles was that the Spanish royal family was in Farnese's direct line of succession, meaning that an enemy dynasty stood to inherit the Constantinian Order.

The Habsburg monarchy (the lands ruled directly by Charles) had enjoyed a string of military successes against the Ottoman Empire under the general Prince Eugene of Savoy, and an eventual "recapture" of Byzantine territory seemed plausible.

[1] His genealogies were backed up by an extensive number of forged diplomas and documents which served to indicate recognition of various invented ancestors by past popes and Holy Roman emperors.

[35] Lazier soon assumed a large set of Byzantine imperial dynastic names,[24] claiming connections to the Angelos, Komnenos, Laskaris and Palaiologos dynasties.

Presenting himself as the rightful heir of the Byzantine emperors, Lazier styled himself as the princeps de genere Imperatorum Orientis ('prince of the line of the empire of the east').

One of the Latin renditions of his full title reads:[35] Dei gracia ex genere imperatorum Flaviorum Augustorum Romanorum, moxque Constantinopolitanorum ortus, jureque successionis hereditariæ actionis legitimus princeps Trapezundæ, Lazy, Mediæ Ciliciæ, totius Armeniæ, Medinæ, Jordanorum, Colchidis, Hyerosolimæ, insularum Cypri, Ægypti, Galatiæ, Daciæ, Heracleæ, Epiri, Candiæ, Peloponesi, Bulgariæ, Macedoniæ, Alexandriæ, Mesopotamiæ, Joniæ, Babyloniæ, Persiæ, utriusque Arabiæ ac totius Asiæ rex, magnus dux Isauriæ, Zechiæ, Chataniæ, Missiæ, Boetiæ, Bithiniæ, Paphlagoniæ, Lucæ, Onei, Synopis, Pamphiliæ, Anatoliæ, Hellesponti, Epidauri, Moldaviæ, Valachiæ, Corinthi, Thebarum, Athenarum & Larissarum princeps, liber comes insulæ Cephalinæ, Dirachy, Drivasti, dominus dell’Ales sive l’Asiæ, ex sacri Romani imperii proceribus ac comes Palatinus, imperialis supremi angelici & imperialis ordinis aureatæ militiæ Constantinani & Heracliani equitum sancti Georgi magnus magister.

[38][39] In one document, dated to December 1721, the brothers John Matthew and Peter Ludovisi, granted landed titles in the Peloponnese, are assured that as soon as the Ottomans are driven out from the peninsula, either through a peace treaty or force of arms, they will be instated there and be able to rule "forever".

Several of his own documents reference the existence of a virtual Byzantine Empire as a present (and not defunct) entity, effectively envisioned as a government in exile under Lazier.

[39] The German historian Christian Gastgeber considered Lazier's activities to effectively amount to both re-founding the Byzantine Empire as a political (albeit landless) entity and as marking the foundation of his own imaginary realm.

[42] The British author Guy Stair Sainty believes that Lazier's activities helped, if ephemerally, to inspire the crusading sentiment among Western Europeans once more.

[36] Lazier's determination and support by a figure as powerful as the Holy Roman emperor presented a real threat to Farnese's continued tenure as grand master of the Constantinian Order.

[43] Although Lazier's position must have been considered doubtful even to his contemporaries, he was able to operate freely from the imperial lands of the Holy Roman Empire, which suggests that he enjoyed the full protection of Charles.

Some third-party writings concerning the Constantinian Order written as late as 1733 still refer to the ongoing dispute between Farnese and Lazier, as if the two claimants both held legitimate claims to the position of grand master.

[46] Imperial support appears to have been fully gone by 1735; some sources suggest that Charles in that year bestowed the position of grand master of the Constantinian Order upon Radu Cantacuzino, who claimed descent from the Byzantine Kantakouzenos family.

[47] Radu Cantacuzino, who used the full Latinized name Ioannes Rodolphus Contacuzenus Angelus Flavius Comnenus, was a forger similar to Lazier and he had claimed Byzantine ancestry and dignity for several years prior to receiving Charles' recognition.

Though his support had faded[47] and he had grown poor, Lazier continued his pretensions until his death[27] and he died with a still sizeable audience that recognized him as the legitimate grand master and a true descendant of the Byzantine emperors.