No but it can kill a fox
No.
It is unlikely that a fox would kill a dog UNLESS it was of a small variety and also a non aggressive type. Foxes are naturally shy animals and would normally eat rabbits, voles and earth worms. They are a major pest to hens and will kill more than they carry off and this is to do with the history of foxes who in the wild and in cold climates will kill everything they can and then store what they could. One thing to watch with foxes is that should you have a family pet die, bury it deep as foxes will dig up the animal and cart it off. I have lived in the countryside for 60 years and I have never heard of a fox killing a dog. My own dog is a fell terrier ( border/lakeland cross ) and he is more than a match for any fox. Foxes, unless they are an old dog fox are quite small and slender and cats and dogs can inflict injuries on the fox and that is why the incidences of fox attacks are small and often steeped in folklore.
the fox sneaks until the pray is hopples and attacks for the kill
they don't
Larger species of fox can and will kill and eat a raccoon.
Arctic Foxes do not kill their young.
The original Robin Hood was human, while Disney's depiction was an anthromorphic fox.
Kill It
is it illegal
Yes:
Golden eagles can kill the Catalina Island Fox.