SMS Viper was an ironclad gunboat of the Wespe class built for the German Kaiserliche Marine (Imperial Navy) in the 1870s.

The ships, which were armed with a single 30.5 cm (12 in) MRK L/22 gun, were intended to serve as part of a coastal defense fleet.

She was still in service during World War II, and was slated to participate in Operation Sea Lion, the planned invasion of Britain.

The decision was finalized based on the fleet plan conceived by General Albrecht von Stosch, the new Chief of the Kaiserliche Admiralität (Imperial Admiralty), in the early 1870s.

He envisioned a fleet oriented on defense of Germany's Baltic and North Sea coasts, which would be led by the ironclad corvettes of the Sachsen class.

The ship was fitted with a waterline armor belt that was 102 to 203 mm (4 to 8 in) thick, with the thickest section protecting the propulsion machinery spaces and ammunition magazine.

[6] Viper was recommissioned on 20 August 1885 for training exercises carried out with her sister ships Wespe, Salamander, and Mücke, which were led by the screw corvette Stein.

Viper next returned to service on 16 August 1887, and that year, she and the rest of the gunboats in the North Sea joined the main fleet for the annual autumn exercises.

[5] On 15 August 1888, Viper was recommissioned, under command of Kapitänleutnant (KL—Captain Lieutenant) Oskar von Truppel, for another brief training period that lasted until 15 September.

Viper arrived on 8 May and was used to remove significant sections of armor plate and the battleship's main guns in an attempt to lighten the vessel enough that she could be pulled free.