Andre Norton's Plague Ship (1956) featured the felinoid Salarik along side the ship's cat.
Poul Anderson's Ensign Flandry (1966) had the Tigres as major players.
Marion Zimmer Bradley
How can I not mention Aisha Clanclan (エイシャ･クランクラン) from Outlaw Star (1997-today)? There are hordes of nekojin in manga and anime, but she's one of the most memorable.
UPDATE: I forgot Alan Dean Foster's felinoid Tran and the related Golden Saia from his Icerigger Trilogy.