What eats caterpillars?

Many different species of birds.
Birds, Lisards, Frogs,
Carterpillars are large, nutritous and (more importantly) very slow. This makes them ideal food for such animals as Birds, Hedgehogs, various Rodents and even come other Bugs like ants will be pleased to eat a caterpillar. I am told that when hungry a fox or a badger will resort to eating bugs, this would probably include caterpillars.
Birds eat caterpillars. Assassin bugs and Spiders are also predators to caterpillars. The Tachinid fly is a pathogen that can be detrimental to caterpillars.