The Klingon D7-class battle cruiser was a warship that served as the backbone of the Klingon Imperial Fleet from the late 2250s through the 2270s. The Romulan Star Empire began using the same design by 2268 as a result of the brief Romulan-Klingon alliance. By the 2270s, the D7 was largely replaced by the newer K’t’inga-class cruiser, which was similar in design.

Ship Model (Physical)

As portrayed in Star Trek: The Original Series - “Elaan of Troyius” (TV, 1968)

The D7-class studio model was originally designed by Matt Jefferies. He explained that it had to be “instantly recognizable as an enemy ship” and that “it had to look threatening, even vicious.” He took an aerodynamic approach to his design, taking qualities of “a manta ray, shark, or bird-of-prey” as inspiration. Another requirement of the design was that it had to look comparable to the Enterprise in terms of equipment, power, and size, so that it would be understood as a formidable threat. The model itself was constructed by Gene Winfield’s AMT-opoearted “Speed & Custom Shop”, the same outfit that had constructed the various models used as the shuttlecraft Galileo during The Original Series’ first season.

The model was initially filmed as a Klingon battle cruiser for the production of the third season episode “Elaan Of Troyius”. However, in an effort to get more use out of the both expensive and visually impressive model, it was also used as a Romulan ship in the later-filmed episode, “The Enterprise Incident”, which contained a line from Spock indicating that the Romulans were using Klingon designs. An unrelated production decision caused “The Enterprise Incident” to air first, resulting in the first appearance of the D7-class battle cruiser to be that of a Romulan ship.