I'd wonder how a cat could terrorize an entire neighbourhood if I hadn't met a completely insane fluffy tabby a few years ago. The people who owned him had to shut him in a room before allowing guests in their house, because he was so territorial that he would attack, claw and bite anyone other than family members. The person I was with had some business with the owner, who had kitty out on a leash when we arrived. As soon as we stepped out of the car, kitty was throwing himself at the end of the leash, spitting, growling and snarling as the owner tried to corral him and haul him inside.