Genghis Rex is Ruler of the Tyrannos and the Great Ruler of Reptilon in the 1987 animated TV series Dinosaucers. The planet Reptilon was united by the conquests of his ancestors centuries ago and he ascended to the throne during a time of crisis. Reptilon has for centuries relied on an element known as Dinocium for energy, an element growing scarce. Additionally universal peace has lent to a larger population then the planet's habitable regions can sustain. In light of these issues Genghis Rex announced plans to conquer and colonize Reptilon's nearest habitable neighbor, Earth. The public at large has supported this endeavor though a minority, the Dinosaucers, have actively worked against it seeing conquest as not vital to the settlement of Earth and preferring a trade relationship with the natives over subjugation for resources. The Dinosaucers and their small state successfully achieved a semi-autonomous status on Reptilon in light of the debate over Earth. Genghis Rex and his sister, Princess Dei (regent of Reptilon while Genghis Rex is away) made plans to apprehend the leaders of the small nation (the Dinosorcerer and Dinosorceress) for providing equipment to the Dinosaucers who have been actively disrupting the colonization efforts on Earth but failed to do so. 
- Sister: Princess Dei - Princess Dei is Genghis Rex's sister, and Regent of Reptilon during his stay on Earth.
- Unrequited Romantic Interest: Teryx - Teryx and Genghis Rex had a relationship in the recent past, but she broke things off with him stating that her heart belonged to another. Something she had to reiterate when Genghis Rex, on Earth and concerned at being the only individual in five generations of his family to become the Genghis Rex with out a Queen to rule by his side, again approached her with his grandmother's crown and expressed how he can't get over her. Genghis Rex has at times acted in frustration of this matter in other ways, at one point specifically targeting Teyrx with deadly force.  They do end up working together for a time to combat the Sabercat pirate raid on Earth, at which point Teyrx expresses that she can't be with him so long as he plans to conquer Earth. 
- Advisor: Ankylo - Ankylo is the most devoted servant of the Genghis Rex, and often provides encouragement, flattery, and in general optimism to the operations on Earth. His advise in regards to operations on Earth tend to fail due to a misunderstanding of Earth's technology and customs. While the other Repilonians under Genghis Rex generally find Ankylo annoying Genghis Rex continues to keep him around if only to have someone around with faith in the operation.
- Former Comrade: Allo - Allo served under Genghis Rex during a Sabercat Pirate raid on Reptilon prior to Allo's nation separating it's self from Tyranno Rule (though their status is semi-Autonomous with Tyranno Law, global law, still applying). Genghis Rex has admiration for Allo's convictions and has said of him that he's a good soldier, but when it comes to the fate of Earth Allo and Genghis Rex do not see eye to eye and it's Allo who leads the group disrupting colonization efforts on Earth.
- Episode 9 That Sinking Feeling
- Episode 57 Sabertooth or Consequences
- Episode 63 I've Got Those Reptilon Blues Again Mamma