The Kzinti, originally created by Larry Niven, made an appearance in the Gamma Quadrant sourcebook. Fellow fan Saul Schimek wrote the following Species profile for the Kzin, which he posted in the Star Trek Adventures RPG group on Facebook. We have formatted it a little and presented his work as a PDF, with his permission. He also points out that there is more on the Kzinti at this page, from an old Traveller write-up.