Luba

Possessing a pair of bat wings, a prehensile tail, and two more claws per foot than the average cat, Luba was created by Hank McCoy as a hypoallergenic pet for his son Alex. Often referred to by Hank as his "most adorable flying crime against nature", Luba has a normal feline personality, and a tendency to stalk (but not injure, upon penalty of being sprayed with water) the Aeslin mice. And to wake Alex by dropping five feet and landing on his chest at 4am, because yes. Normal feline personality.

The picture, obviously, is of Luba as a kitten; she's several years older now, but still adorable.

(Luba is originally the creation of Suzene Campos of fanfic fame. We just borrow her because, well, flying cats are fun!)