Leontius (Greek: Λεόντιος, Serbian: Leontije; fl.
An ethnic Greek from Adrianople, Leontius was a disciple of Methodius, the Metropolitan of Belgrade between 1791 and 1801.
Some also believe that he was involved in the murder of Vizier Hadži Mustafa Pasha, which resulted in the Sanjak of Smederevo being ruled by the renegade Janissaries known as the Dahije.
Leontius supported the Dahije, and had Serbian abbot Hadži-Ruvim captured by them upon hearing that a uprising was planned (see also Slaughter of the Knezes).
In 1810 Leontius and Russian agent Konstantin Rodofinikin plotted against Karađorđe.