The 40.6 cm SK C/34, sometimes known as the Adolfkanone, was a German naval gun, designed in 1934 by Krupp and originally intended for the early H-class battleships.

The H class was a series of battleship designs for Nazi Germany's Kriegsmarine, which were intended to fulfill the requirements of Plan Z in the late 1930s and early 1940s. The first variation, "H-39", called for six ships to be built, essentially as enlarged Bismarck-class battleships with 40.6 cm (16 in) guns and diesel propulsion. The "H-41" design improved the "H-39" ship with still larger main guns, eight 42 cm (16.5 in) weapons, and reinforced deck armor. The Construction Office of the Oberkommando der Marine (OKM) concluded their work with the "H-41" design, and were not involved in subsequent plans. Two of them, "H-42" and "H-43", increased the main battery yet again, with 48 cm (18.9 in) pieces, and the enormous "H-44" design ultimately resulted with 50.8 cm (20 in) guns. The ships ranged in size from the "H-39", which was 277.8 m long on a displacement of 56,444 t, to the "H-44", at 345 m on a displacement of 131,000 t. Most of the designs had a proposed top speed in excess of 30 knots (56 km/h).