Kobali Prime was the home planet of the Kobali, a Delta Quadrant species who reproduce by reanimating and genetically altering the dead of other races.
The planet is referred to in the sixth-season episode Ashes to Ashes. Ensign Lyndsay Ballard, killed on an away mission, was given a burial in space. The Kobali recovered her body, rewrote her biology and raised her as Jhet'leya in the household of a man named Q'ret.
Unlike most of those so transformed, she keeps her memories. After two years she steals a shuttle from Kobali Prime and spends six months chasing Voyager. The Doctor restores much of her human appearance, and she tries to pick up her old life and her friendship with Harry Kim.
She finds that her tastes, language and instincts are now Kobali. When Q'ret arrives with warships to reclaim her, she goes back with him to prevent a battle.