Kos'karii

From Memory Alpha, the free Star Trek reference

In Klingon mythology, the kos'karii are pale, serpent-like creatures which inhabit the blood-red waters crossed by the Barge of the Dead on its way to Gre'thor. They attempt to lure dishonored souls to them with voices of friends and loved ones, and then drag them into the water. (VOY: "Barge of the Dead")