Si Papa Leon XII (namundag Annibale Francesco Clemente Melchiorre Girolamo Nicola della Genga; 2 August 1760 – 10 February 1829) iyo an pamayo kan Simbahan Katoliko asin namamayo kan Papal States poon 28 September 1823 sagkod sa saiyang kagadanan kaidtong February 1829.[1]