Girolamo Petri (1806 - 1871) was an Italian lawyer and official in the Roman Catholic Church. Born in Onano (Viterbo, Lazio), Petri was the son of a Vatican civil servant. He studied law and went on to work as a lawyer for the Church until he was appointed to a position as a senior official in the State Secretariat (the curia body that oversaw the Church's international operations) in 1847. Due to his passion for cartography, Pope Pius IX bestowed upon Petri the task of creating an atlas of the Catholic world, L'Orbe Cattolico ossia Atlante Geografico Storico Ecclesiastico. Petri noted that, in making this atlas, he used only 'the most trusted sources', such as maps in the Vatican archives and from overseas dioceses.