While Smithsonian's Air and Space Museum has proudly displayed the original Star Trek U.S.S. Enterprise production model used for the 1966 television series, the museum also has the model of the ship used by that's show's antagonists, the Klingons.

While Klingons appeared early in the Star Trek TV series, their D7 Battle Cruiser didn't appear on screen until the third season. In remastered episodes created in 2006, the ship has been inserted into establishing shots in those earlier episodes.

The NASM's Enterprise is nearly the size of some of its aircraft, at 11 feet. The Klingon Battle Cruiser, however, is a more familiar model size, at just 30 inches in length.

Paramount's Star Trek art designer Matt Jefferies, who created the Enterprise design, styled the Klingon ship. He is said to have sought to evoke the menacing appearance of a manta ray with the ship's design.

Once the Klingons obtained Romulan cloaking technology that turned ships invisible, there was nothing to show. But when uncloaked, this is how the rival warships looked. A 2006 Christie's auction saw the larger successor model used in the Star Trek films sell for $102,000. You can see that more detailed model in action this clip from the movie.