The fat one himself.
Snorlax is some mutated fat guy that eats more than he should. In fact, he once ate an entire pickup truck, but then he barfed it up, only to eat it again, then he asked for desert. He likes eating so much, he will even eat his own limbs (this is why it is common to find Snorlaxes without arms or legs).
Snorlaxes are an endangered species, but we can not hunt them to finish them off, because they have Super Fat. That is why we have to kill every little Munchlax before they grow into full sized Snorlax. Aren't we so nice? Dr N. Brio claims he invented a Snorlax-killer, but he's just making stuff up again. We know it's really just a bucket of old socks that says "SNORLAX KILLER" on it.
The only thing Snorlax likes more than eating, is sleeping. The record for the longest a Snorlax has ever slept, is 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,001 hours. If anyone knows how many years that is, please let us know, even though we are probably smart enough to figure it out ourselves if we wanted to.