The Klingon noble, father of Duras, who secretly passed Khitomer's defence codes to the Romulans in 2346 and whose treason the High Council concealed by blaming Worf's father.
Ja'rod was the head of the House of Duras in the mid 24th century and a bitter rival of Mogh. He conspired with the Romulans and transmitted the defence access codes of the Khitomer outpost, allowing the attack of 2346 in which some four thousand Klingons died. Ja'rod was killed there as well.
The truth emerges in The Next Generation episode Sins of the Father. Captured Romulan records show that a Klingon betrayed Khitomer, and because his son Duras now commands enough support to split the Empire, Chancellor K'mpec and the Council pin the crime on the dead Mogh. Picard and Worf uncover the deception through the testimony of Worf's old nurse Kahlest.
Ja'rod is never seen. His family's Romulan ties resurface when Duras's sisters Lursa and B'Etor fight the civil war of Redemption.