- For other uses, see Kos'Karii.
In Klingon mythology, a Kos'Karii (also Kos'karii) was a pale, serpent-like creature. Within the realm of the Fek'Ihri, the Kos'Karii inhabited the blood-red waters crossed by the Barge of the Dead on its way to Gre'thor. (VOY episode: "Barge of the Dead")
The Kos'Karii were at least as long as an adult Klingon. They attempted to lure the condemned souls of the dishonored warriors and feed on them. To that end, the prospective victims heard siren-like voices emulating their friends of loved ones. (VOY episode: "Barge of the Dead")
The mythology surrounding the Kos'Karii inspired a tradition. To celebrate the arrival of a new year, young Klingon warriors would wade into rivers and lakes to fish for ghotI'. Using their bare hands and operating in frigid waters, this was a form of ice fishing. The fishers then offered the captured ghotI' as bait for a giant ghargh. Once this creature appeared, the warriors attempted to defeat it. They believed this symbolic act would keep the Kos'Karii from tempting warriors from the path of honor. (STO - "Q's Winter Wonderland" mission: "Klingon Ice Fishing")
In 2376, B'Elanna Torres experienced visions in which was a passenger aboard the Barge of the Dead as it sailed towards the gates of Gre'thor. Hij'qa told Torres that the voices she had heard were the Kos'Karii, and not her crewmates on USS Voyager. Later, B'Elanna's mother Miral mistook her daughter for a Kos'Karii siren. (VOY episode: "Barge of the Dead")
From 2409, year 2016 in local reckoning, q introduced ice fishing based on the new year tradition to his Winter Wonderland. A Klingon ice fisher explained the tradition to visitors. In a twist of humor, q had replaced ghotI' and ghargh with gummy fish and a Gummy Kos'karii. The Gummy Kos'Karii was a giant version of the Gre'thor Kos'Karii. (STO - "Q's Winter Wonderland" mission: "Klingon Ice Fishing")