Psychotic crime boss with a passion for torture and sadism and a heavy Russian accent. He believes in money and power and that fear is a perfect tool to achieve both. Very fixed on the concept of reputation and this fixation is a driving force behind how he runs his empire. He first appears in the episode Train Job in which he offers Mal and the crew a job robbing a train for him, they discover that the booty they have swiped is medicine and decided to return it. This infuriates Niska - exacerbated by the fact that Mal killed Crow (Niska's head thug) by kicking him into one of Serenity's engines.
The next appearance of Adelei Niska is in War Stories, in which he captures Mal and Wash and subjects them to physical and psychological torture on his Skyplex. During this scene he quotes a philosophical passage from a warrior poet/psychotic dictator, showing that he is very intelligent (as most evil geniuses are). During the crews' rescue Niska seems to disappear and his Torturer (and possible Crow replacement) is killed by Mal using a torture device specially designed by Niska himself, which seemed to attach to the victim's skin with claws or tendrils that cut at their flesh. The Torturer is fighting Mal by an abyss in the middle of Niska's Skyplex and is pumped full of bullets by Jayne, ZoŽ and Wash and his corpse falls into the abyss and disappears from view.
Niska himself is nowhere to be seen
Played on the show by Michael Fairman.