American Bobtail kitten! What a cutie! I love the lynx tipping on the ears and longer cheek fur, it really gives the cat a wild look. (Kind of a relief to know that their short tail is due to their genetics, and not docking.)
Manx Cat is a breed of domestic cat originating on the Isle of Man in the British Isles, with a naturally occurring mutation that shortens the tail. Many Manx have a small stub of a tail, but Manx cats are best known as being entirely tailless; this is the most distinguishing characteristic of the breed, along with elongated rear legs and a rounded head.