The Klingon system was the primary star system of the Klingon Empire and the location of the planet Qo'noS. (TNG: "Sins of the Father"; Star Trek VI: The Undiscovered Country)
In 2151, it took four days for Enterprise (NX-01) to travel from the Sol system to the Klingon system. (ENT: "Broken Bow")
- Numerous fan-theories, some of which involve the use of subspace-conduits, have evolved, as the Enterprise was not able to exceed Warp 4.5 at that time, presumably placing the Klingon system extremely near to Earth.
- The term "Klingon system" was only referenced once, by Kurn in "Sins of the Father." The star, which was seen as the USS Enterprise-D and IKS Bortas approached Qo'noS in "Redemption", was never given a formal name.