The Felidae are slender felines with exotic features similar to oriental cats. Francis remarks he's never seen their breed before. Nhozemphtekh is the only Felidae cat seen, set apart from the others with her blazing yellow eyes, slender and angular facial features, and golden pelt.
Their names are often long, elaborate, and very hard to pronounce.
The origin of the Felidae cats is unclear. What is known is that Claudandus oversaw their creation for years, claiming that he "started with a single pair" and broadened out their numbers, carefully choosing "racially suitable" males to breed the females and eliminating males who tried to add their genes to the breed. Females too, which is why Solitaire was murdered.
The idea of the Felidae cats seemed to come not from Claudandus, but Julius Preterius himself. When Dr. Gray and Ziebold walk out on his experiments, he speaks of breeding a superior race of cats and indeed, had started breeding cats to use as test subjects. Claudandus had similar sentiments, but planned to use the cats to take down the human race.