The Sphinxian treecats from the Honor Harrington universe. While not actually cats they beat any Earth cat in pure awesomeness. They have centimetre long stone hard claws and fangs, the ability to take down fully grown humans with ease, the fact that they're psychic empaths, that bond to humans psychically. Not to mention their prehensile tails are as long as their bodies, and they have six limbs, with the foremost ones having actual hands. The winner of all of them in Nimitz, the treecat bonded with Honor her self. He's a trickster, with a wicked sense of humour, and saved a lot of important people in the Honorverse. Also the name he has among treecats is "Laughs Brightly."
Runner up to the treecats is Michelle Hankey's steward's cat in the Honorverse, Dicey, a huge example of a Maine Coon cat, who can identify cat lovers on sight. Plus he's all scared up from beating the hell out of other cats. What a badass.
