Someone who's ravening is ferociously hungry, like a wild animal. A ravening monster in a horror film hunts its prey for food.
While a ravening wolf is fierce and brutal in its hunger, you can also use ravening to describe someone who acts wild or brutish in other ways. A businessman's ravening greed is so savage that he doesn't care who's hurt in his pursuit of money. A crowd of ravening children might dive for candy beneath a piñata, shoving each other out of the way. A now obsolete verb, raven, or "prey, plunder, or devour," is the root of ravenous.