The Kzin (plural Kzinti) are a fictional, very warlike and bloodthirsty race of Felinoid aliens in Larry Niven's Known Space series.
Kzinti in other science fiction
The Kzinti also appeared, along with allusions to slavers and stasis boxes, in The Slaver Weapon, an episode of Star Trek: The Animated Series written by Niven. They were incorporated into the Star Fleet Universe where they became a powerful empire known as the Kzinti Hegemony, mortal enemies of that universe's Lyran Star Empire - although it is alluded that the Kzinti and Lyrans share common ancestry, a claim both sides violently reject. They have not otherwise been mentioned in the mainstream Star Trek universe.
The instruction manual for the PC game Star Fleet Command clearly refers to the Kzinti by name in the background story for the rival race, the Lyrans. This race is introduced in Star Fleet Command II: Empires at War by simply changing the Kzinti Hegemony to the Mirak Star League.
Kzinti are thought to have influenced the creation of the similarly Felinoid Kilrathi, the primary antagonists of the popular Wing Commander video game series of early-to-mid-nineties. Whether this is true or not, a small part of Wing Commander II takes place in a region of space called the Niven Sector.
Background and history
Kzinti evolved from a plains hunting cat, stole their current space-faring technology, and bred (most) of their own females into sub-sapience. They are larger than most humans, they have large membrane ears, a cylindrical torso without a spine, and large fangs and claws. A small percentage of Kzinti are stunted and exploited addictive telepaths, and they aren't legally allowed to breed.
They are the first on-going alien contact that humanity has within the Known Space universe. The onset of their relationship with humanity ends the golden era, where humanity had almost completely succeeded in re-writing history into a non-violent whitewash, and where organized violence was only known about by roughly 1 in 10 people, and there was no interpersonal violence, except occasional out-bursts in the asteroid belt where medical and psychological care were spread too thinly.
The Man-Kzin Wars
The Kzinti contact a laser-driven exploration ship, with vast technical superiority, gravity planers, telepathy, and a vast empire. They attempt to kill the human crew in a flashy manner when the telepath learns that they don't even understand the concept of weapons, and fail. Thus began the First Man-Kzin War.
In the course of the First Man-Kzin War, the kzinti attacked the human colony of Wunderland, in the Alpha Centauri system. A passing Outsider ship sold the colony the secret of hyperdrive, a technology not known to the kzinti. A hyperdrive ship was dispatched to warn Sol system of the threat; the resources of Earth and the Belt were then directed against the kzinti invaders, who were helpless against the faster human ships.
In several different stories by other authors playing in the universe we see a number of Man-Kzin wars take place. The net effect of these wars is summed by a retrospective comment from Louis Wu in the Ringworld novels: "The kzinti aren't really a threat. They'll always attack before they're ready." With insufficient logistics or technological advantages, each Man-Kzin War results in the confiscation or liberation of one or more colony planets by the humans. In this way humanity contacts the Pierin and Kdatylno, former slave species, and takes over worlds such as Canyon (formerly Warhead) and Fafnir (formerly Shasht).
Eventually (in Ringworld) we learn that the Kzinti were deliberately led to encounter humanity by the Pierson's Puppeteers, who lured the Outsiders to Wunderland in the first place. The Puppeteers hoped that the culling of more than a quarter to a third of the aggressive members of the Kzin with every war would result in a more peaceful race. This shift in kzinti attitudes has in fact occurred, although the kzinti themselves do not think very highly of the changes.
Kzinti in the Star Fleet Universe
The Kzinti in the SFU have fought wars with all of their neighbours, the Federation, the Klingon Empire and their perennial nemeses, the Lyran Star Empire, and are long-standing allies - or more accurately, co-belligerents - of the Hydran Kingdoms. The Hegenomy eventually formed a tentative accord with the Federation and allied with them in the General War, but they have been involved in major wars with the Klingons and Lyrans, such as the Four Powers War and the General War itself, in which a substantial region of their territory was occupied by their Coalition enemies and two full-scale assaults were made on the Kzinti homeworld of Kzintai. Eventually with Federation assistance they forced the Coalition forces from their territory, but after the War ended they were involved in a Civil War as a disgruntled faction - which had been opposed to the Hegemony's ruling Patriarch and sought refuge and developed a power base in the WYN Cluster, launched an attempted coup of the Hegemony itself in the WYN War of Return
- Fan page about the Kzin language, including a Kzinti font (http://www.larryniven.org/kzin/language.htm)