Marco d'Aviano (1631-1699) was a Capuchin friar. Born Carlo Domenico Cristofori in Aviano, Republic of Venice. Deeply inspired by his encounter with the Capuchins, he felt that God was calling him to enter the order. In 1648, he entered the novitiate of the Capuchins. A year later, he professed his vows and was given the name "Friar Mark of Aviano". Marco d'Aviano's life changed unexpectedly on 1676 when he gave his blessing to a nun who had been bedridden for some 13 years. Upon receiving Friar Mark's blessing, she was healed.

From 1680 until his death, Marco d'Aviano assisted Leopold I, offering him spiritual guidance and advice for every sort of problem: political, economic, military and religious. Marco d'Aviano was also appointed by Pope Innocent XI as Apostolic Nuncio and Papal Legate. An impassioned preacher, Marco d'Aviano played an important role in maintaining unity among the 'Holy League' armies of Austria, Poland, Venice, and the Papal States under the leadership of the Polish king Jan III Sobieski. In the decisive Battle of Vienna (1683), the 'Holy League' armies succeeded in repulsing the invading Ottoman Turks.