The D7 class BattleCruiser was the first starship class used widely in the Klingon Empire. The first ship was launched in 2245, 2 months before the USS Enterprise. This class formed the backbone of what would become the Klingon Defense Force, for the next 20 years. It's basic design has been copied and upgraded numerous times. Klingon Designers and Tacticians worked together designing the ship, which was influenced by Starfleet's Constitution Class.

Starfleet designers put the bulk of the weaponry on the forward command saucer, while having the engine nacelles sweeping out at the back made it easy to maneuver. The Klingons did a rather good job putting it all together. The engine nacelles were attached to a small secondary hull/engineering section. Extending from that was a long boom at the end of which was the spherical command pod. The Weapons were also more evenly balanced, with 1 torpedo tube at the rear and the other at the front of the command pod, while 6 disruptors are mounted on the secondary hull and the remaining 4 are flanking the forward torpedo launcher.

During their short lived alliance with the Romulan Star Empire in 2267, the Klingons gave them the D7 design in exchange for cloaking technology. Other than that, the D7's have led relativly basic lives, becoming entangled in few skirmishes. The D7 design was copied and updated extensivly to become the K'Tinga class BattleCruiser, when that ship was being developed in 2268. At the present, no D7's remain in active service. Most were either decomissioned or scuttled except for 12 which remain on training duty, outfitted with modern technology.