PPN may refer to: Guillermo León Valencia Airport Pre-Pottery Neolithic Nigerien Progressive Party-African Democratic Rally (Parti Progressiste Nigérien) Pingat Pangkuan Negara, a Malaysian honour Pedunculopontine nucleus Principal protected note, an investment contract Protoplanetary nebula Parameterized post-Newtonian formalism, for calculations on gravity Pacific Patriot Network PPN+ or [(Ph3P)2N]+ cation, produced from Bis(triphenylphosphine)iminium chloride