The Graf Zeppelin was Germanys only aircraft carrier in World War II - but it was never completed and never saw action. The ship was laid down on December 28th 1936 at Deutsche Werke shipyard in Kiel as Flugzeugträger "A" and was launched two years later on December 8th 1936. It was projected that the ship would be completed by the end of 1940 - but this never happened. An interesting detail is that in 1935, a German commission visited Japan to inspect the carrier Akagi to gain information about aircraft carrier specific construction details.

In April 1940 the construction was stopped as the focus of Germanys naval construction changed to U-boats and the work on all incomplete major surface ships was stopped. The already installed guns were used for coastal defenses in Norway and the ships was transferred to Gotenhafen (Gdynia).

In 1942 it got obvious that the German Kriegsmarine would need aircraft carrier for further actions of the major surface units and therefore the construction of the Graf Zeppelin was resumed. It was projected to complete the ship by the winter of 1943. The planned naval base for the carrier was Drontheim, at the south end of the Faettenfjord. At the same time, several cruise ships like the Potsdam , Gneisenau , Europa and the Prinz Eugen class cruiser Seydlitz were planed to be converted to aircraft carriers. In December of 1942 the Graf Zeppelin was again transferred to Kiel to continue the construction, but after the the battle of the Barents Sea against the convoy JW51B,  the construction of all major surface units was finally stopped, at this time, the carrier was completed about 80%.

At this time, the 15 cm guns were removed and transported to Norway to be used as coastal artillery ("Marine-Küsten-Batterie" - MKB). Four were installed at MKB 6/514 in Sore Korsnes near the Altafjord in December 1943 and got operational in February 1944. In November 1944 those guns were evacuated to MKB 5/512 in Karlsoy and got operational in January 1945. After the war, these guns were installed at Grotoya near Harstad and used by the Norwegian army until the early 1990s.
Four other guns were brought to Kap Romanov and in use since September 1942. They engaged Russian coastal artillery in Fiskerihalvoya and were blown up in October 1944. There are several versions about the fate of the Graf Zeppelin after the war. One version says that the ship was sunk after a mine hit on its way to the Soviet Union. Another version is that the ship capsized because of a heavy load of equipment stored in it. One possible fate mentioned is that the ship was completed by the Soviets after the war, but this sounds not very realistic at all.

According to new Russian sources, the Graf Zeppelin was sunk after weapons tests in August 1947:

The carrier was moved to Stettin in April 1943 where it was sunk by its own crew on 25.04.1945. Being captured by Russians, Graf Zeppelin was renamed to IA-101 (Floating Base No. 101) on 03.02.1947. On 16.08.1947 the carrier has been sunk as a target ship off Swinemünde.
Graf Zeppelin sank as she "scored" 24 bombs and torpedo hits, including two 1000 kg air bombs. One of them was mounted into the funnel; as it exploded, the funnel was completely destroyed up to top deck, but superstructures of the island remained intact. Two 500 kg bombs, three 250 kg and five 100 kg bombs plus four 180 mm 92 kg shells were used on the ship. All these charges were mounted upon the flight deck and hangar deck. Six training air bombs dropped from the dive bombers and two 53,3 cm torpedoes from the torpedo boat OE-503  and destroyer Slavniy were fired on the ship. The last torpedo scored the fatal hit that finished the destruction of carrier. 23 minutes after the last hit, the Graf Zeppelin sunk.

The wreck of the Graf Zeppelin was found in July 2006 about 55km north of Wladyslawowo (Poland) at 55,3N18,42E. The ship seems to stand upright in a depth of 80m.

The Graf Zeppelins sister ship, the Flugzeugträger "B" was laid down at the Krupp Germaniawerft in Kiel in autumn of 1938, but construction was stopped at the beginning of World War II. In February of 1942, the ship was scrapped in the shipyard.