Kzin was an inhabited planet in the Alpha Quadrant. This was the homeworld of the Kzinti. The leader of the Kzinti government was the Highest of Kzin.
In the late 21st century, the Kzinti fought a series of four wars with Humankind, and lost them all. Under the Treaty of Sirius, they were forbidden all weapons except police vessels and related equipment. Nevertheless, some Kzinti illegally possessed phasers and sought other armaments.
In 2269, two Slaver stasis boxes were discovered by archaeologists on Kzin. One was turned over to Starfleet, and the other was kept by the Kzinti, but found to be empty. With the secret support of their government, a group of Kzinti privateers led by Chuft-Captain of the ostensibly stolen police ship Traitor's Claw undertook a mission to reacquire the unopened box and gain control of a powerful Slaver weapon hoped to be inside. This weapon self-destructed and killed the privateers before it could be returned to Kzin. (TAS: "The Slaver Weapon")
The location of Kzin in the Milky Way Galaxy was labeled on a star chart in Captain James T. Kirk's quarters aboard the USS Enterprise-A in 2293 and at Starfleet Headquarters in 2364. (Star Trek VI: The Undiscovered Country; TNG: "Conspiracy")
In 2365, the location of Kzin was labeled in a Subspace Comm Net Ops star chart, which was seen in the courtroom on Starbase 173. This planet was linked to the Sol system. (TNG: "The Measure Of A Man")
In August 2024, an annotated computer paste-up of this star chart was put up for auction in the Entertainment Memorabiliia Live Auction: Los Angeles Summer 2024 by Propstore Auction. [1]
In Larry Niven's Known Space Universe, the central star of the Kzinti's homeworld was identified as 61 Ursae Majoris.