Marco Gradenigo was a 13th-century Venetian nobleman, senior provincial administrator in the Venetian overseas empire and a military commander. He was involved in three major conflicts: the War of the Euboeote Succession, where Gradenigo organized a league of the lords of Latin Greece against the Principality of Achaea; the defence of the Latin Empire against the Empire of Nicaea, which failed with the Reconquest of Constantinople by the Nicaeans during Gradenigo's tenure as Podestà of Constantinople; and the naval operations of the War of Saint Sabas against the Republic of Genoa.