I lost a few cats and one puppy to coyotes that lived in the hills in back of our old house. They would get so hungry at night that they would actually jump our gate and snatched the puppy, carrying him over the fence. It was actually my brother's puppy, and I remember him crying for a week about the loss of that sweet pup. So sad.
The only other cat I lost was an indoor/outdoor cat. She was mean and tough, so I don't think anyone would have just taken her. She didn't let anyone but us pet her. We searched our nearest humane society for a couple weeks but she was never turned in. I never knew what happened to her.
These days we keep all our pets inside the house. I'm too afraid of cars, dogs and people who just steal other people's pets to let them outside.