P11, P-11 or P.11 may refer to: In military : Heckler & Koch P11, a special purpose Heckler & Koch pistol designed to be used underwater Heckler & Koch HK4, a pistol produced by Heckler & Koch, which was used by the German military as the "P11" Kel-Tec P-11, a semi-automatic pistol designed for concealed carry PZL P.11, a fighter aircraft used by the Polish Air Force during the invasion by Germany in 1939 In science and academia : Pioneer 11, a satelite launched to explore Jupiter and the… (More on P11)