The Karl series of mortars (Mörser Karl) (Gerät 040) were built by the Germans during the Second World War. In total, six Karl-class guns were manufactured. These guns had the names Adam, Eve (1st Batt.), Thor, Odin (2nd Batt.), Loki, and Ziu.

At first the Mörser Karl was developed for use in the campaign against France, but as France had surrendered, it was put to use for the first time on the Russian front and saw action in the siege of Sevastopol. It was also employed in the Brest-Litovsk and Warsaw uprisings.

The Mörser Karl had a range of 6,800 m at best. To extend the range, a barrel of 54cm calibre and 7.1m in length was manufactured. Three Karls were equipped with it instead of the 60cm calibre gun to become the 54cm Mörser, designated Gerät 041, with a longer range of 10,400m. The ammunition for these monster guns weighed about 2 tons apiece depending on the specific ammunition type. Due to its huge size and concomitant difficulty of use, its effect on the outcome of the war was probably minimal, but it undoubtedly had a marked psychological impact on those at the receiving end of its shells.