Albino Luciani was the Patriarch of Venice, prior to his ascension to the throne of St Peter. He was much loved as a Pope, both for his humilty and his general joyousness.
His Papal name, John Paul, combined the name of his two immediate predecessors, John XXIII and Paul VI – and was subsequently the name of his successor – largely due to the fact that John Paul I died after only 34 days in office (which makes him the eleventh shortest lived Pope).
His theology was unusually liberal for a Pope, including discussing the possibility of ending the church’s opposition to contraception. For this reason, along with Luciani’s comparative youth (he was 65 when he died, young for a Pope), it is widely rumoured that he was assassinated (which would hardly be unprecedented for a Pope), but no conclusive evidence has ever emerged.