A predator is an animal that eats other animals — or people or companies who act like they do. Lions are predators, but so are pickpockets and some giant corporations.
The word predator started out referring to insects that ate other insects, but has grown to include any animal that eats another animal. We humans like to think of ourselves as the top of the food chain, but scary movies love to disagree, like in the 1987 movie Predator, where creepy aliens try to kill and eat us. Predators don't have to kill and eat you, though; they can also just take your stuff. It's from the Latin word praedator, which means "plunderer," which is more like something a pirate would do.