The Odin class was a pair of coastal defense ships built for the German Kaiserliche Marine in the late 19th century. The class comprised two ships: Odin, named after the Norse god Odin, and Ägir, named after the Norse god of the same name. The ships were very similar to the preceding Siegfried-class coastal defense ships, and are sometimes considered to be one class of ships.

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.