Mogh, father of Worf and Kurn, was an influential citizen of the Klingon Empire. He helped Huraga's House during their blood feud with the House of Duras. He was also a friend of Noggra. Mogh was killed during the Romulan attack on Khitomer in 2346. (DS9: "The Way of the Warrior", "Sons of Mogh"; TNG: "Sins of the Father", "Birthright, Part I")
Duras challenged his honor in 2366 claiming that it was Mogh that gave information to the Romulans that led to their attack. In fact it was Duras' father, Ja'rod, who had betrayed his people by conspiring with the Romulans. However, Worf was forced to accept discommendation in order to protect the Empire due to the power of Duras's family, resulting in his reputation being colored for a time by the stain of his father's alleged crime. (TNG: "Sins of the Father", "The Drumhead")
- Ronald D. Moore's early idea for the Star Trek: Deep Space Nine episode "Soldiers of the Empire" was for Worf and Martok to encounter Mogh in Gre'thor. (Star Trek: Deep Space Nine Companion, p. 448)
- A deleted scene from DS9: "Tacking Into the Wind" saw Worf wish that Mogh was alive to see his son briefly be Chancellor of the Klingon Empire. (Star Trek: Deep Space Nine Companion - A Series Guide and Script Library)
- It is widely assumed that Mogh was the son of Colonel Worf, but this was never confirmed on-screen. The Star Trek: The Lost Era novel The Art of the Impossible uses this assumption, and states Worf was named after his recently-deceased grandfather. Promotional material for Star Trek VI: The Undiscovered Country, including interviews with Michael Dorn, stated that Dorn was playing Worf's grandfather in the movie.
- While Mogh was never seen on camera, a trading card was created for the Star Trek Customizable Card Game using photo elements of both Worf and Kurn, combined together using Photoshop.
- The Art of the Impossible establishes that Mogh served as first officer under Captain K'mpec on the IKS Pu'Bekh. K'mpec noted that while Mogh was a warrior and excellent with a disruptor pistol, he was terrible with a bat'leth. When K'mpec ascended to the Klingon High Council, Mogh became captain of the Pu'Bekh.