I don't know if Klingons "Rest in Peace," and I am not the most informed Trekkie on this or any other planet. But I do know the "Star Trek" universe wouldn't have been the same without its "villainous" Klingons. And first among them was Kang, played by Michael Ansara, who died this week at age 91.
ETA: As many of you have noted, Ansara was a busy busy TV and movie actor, often playing ethnic characters (of which Klingon may simply have been his farthest-flung). More here.