Jeri Taylor pointed out that casting a 14-year-old on “Star Trek” was troublesome. There had been many kids on “Star Trek” in the past, but writing Kar was an issue as they needed a young actor who could convincing play a Kazon murderer. The Kazon, some Trekkies have said, are essentially Diet Klingons, making them brutal and honor-bound in a very similar way. “Star Trek” had never featured a Klingon teen before (Alexander notwithstanding), so there was no precedent. When it came to the casting process, Taylor said the following:

“I thought it was reasonably successful. […] We gave ourselves a very difficult task by writing a part for a 14-year-old young man. We ended up casting Aron Eisenberg, who plays Nog on ‘Deep Space Nine,’ and more people were aware of that than I would have thought. He didn’t look anything the same, but he has a very distinctive voice. It broke the suspension of disbelief and made people say not, ‘Oh, there’s a young man in pain,’ but ‘Oh, it’s Nog from ‘Deep Space Nine.” As soon as the mind is doing that, it’s not involved in the story.”

The Kazon have orange-ish skin like Ferengi, but sport outsize Klingon-like foreheads and shell-liked “horns” on their heads. Ferengi, meanwhile, have outsize ears, large ridged noses, fangs, and lumpy, hairless heads. Despite the makeup, though, Eisenberg was easy to recognize.