Seriously though, get yourself one of those Bengal cats, they'll scare the living **** out of any domestic cats who won't want to leave their house
apparently sprinkling black pepper or cayenne works (thats whats in those spray things apparently) also moth balls keep them away, but these are toxic and dogs eat them and get very ill/dead Another way if you live near a zoo is get something with lion pish on it.
Catch it and rub English mustard on its arsehole. It try's to lick it of it burns its tongue. It will never come back to your domain again, Promise.
The locals near my house in Spain put plastic Coke bottles full of water about their gardens. It keeps the strays away for some reason.
A couple of lurchers should do the trick. The ****ers will murder owt small and furry. They grab them by the neck and the bite and shake snaps them.