SMS Mainz was a Kolberg class light cruiser of the German Kaiserliche Marine (Imperial Navy) during the First World War. She had three sister ships, SMS Kolberg, Cöln, and Augsburg. She was built by the AG Vulcan shipyard in Stettin; her hull was laid down in 1908 and she was launched in January 1909. She was commissioned into the High Seas Fleet in October 1909. She was armed with a main battery of twelve 10.5 cm SK L/45 guns and had a top speed of .