Pope Leo XII, born Annibale Francesco Clemente Melchiorre Girolamo Nicola Sermattei della Genga) was head of the Catholic Church and ruler of the Papal States from 28 September 1823 to his death in 1829.
Leo XII was in ill health from the time of his election to the papacy to his death less than 6 years later, although he was noted for enduring pain well. He was a deeply conservative ruler, who enforced many controversial laws, including one forbidding Jews to own property. Papal finances were also poor, even though he reduced taxes. As a result, Leo XII's reign was unpopular and provoked widespread discontent within the Papal States.