The O class was a planned class of three battlecruisers for the Kriegsmarine (German navy) before the Second World War. Prompted by a perceived lack in ship numbers when compared with the BritishRoyal Navy, the O class' design was born with the suggestion of modifying the P-class cruiser design with 380 mm (15 in) guns instead of 283 mm (11.1 in). The ships were incorporated into the 1939 Plan Z; while an aircraft carrier, H-class battleships and smaller ships engaged convoy escorts, one or more O-class ships would attack the merchant ships.
The O class' design reflected their intended role; a heavy main armament—six 380 mm guns in three dual turrets—for possible encounters with escorting 203 mm (8.0 in)-armed heavy cruisers, enough armor to defend against the same and nothing more, and a high top speed so that they could get away from slower but much better armored capital ships.
- Main Guns: 6 × 38.1 cm (15.0 in) SK C/34 guns
- Sub Guns: 6 × 15 cm (5.9 in) SK C/28 guns
- Torpedoes: 6 × 53.3 cm (21.0 in) torpedo tubes
- Gold Cost: 820