SMS Odin was the lead ship of her class of coastal defense ships built for the Imperial German Navy. She had one sister ship, Ägir. Odin, named for the eponymous Norse god, was built by the Kaiserliche Werft in Danzig between 1893 and 1896, and was armed with a main battery of three 24-centimeter (9.4 in) guns. She served in the German fleet throughout the 1890s and was rebuilt in 1901–1903. She served in the VI Battle Squadron after the outbreak of World War I in August 1914, but saw no action. Odin was demobilized in 1915 and used as a tender thereafter. After the war, she was rebuilt as a merchant ship and served in this capacity until 1935, when she was broken up for scrap.

Coastal defence ships were warships built for the purpose of coastal defence, mostly during the period from 1860 to 1920. They were small, often cruiser-sized warships that sacrificed speed and range for armour and armament. They were usually attractive to nations that either could not afford full-sized battleships or could be satisfied by specially designed shallow-draft vessels capable of littoral operations close to their own shores. The Nordic countries and Thailand found them particularly appropriate for their island-dotted coastal waters. Some vessels had limited blue-water capabilities; others operated in rivers.