Parthenon
Jellyfish are eaten by squid. I believe that this is the biggest threat that they face.
the market economy was the single biggest threat
Churchill thought that Hitler was the biggest threat in WW2
Biggest threat is a landowner with a 22 rifle or 12ga shotgun.
you are
The Parthenon is now an empty ruin, however when built it housed a statue of Athena Parthenos.
That is the correct spelling of the proper noun "Parthenon" (temple in ancient Greece, now ruins).
The pinniped population is decreasing, because of lack of food and global warming, so the killer whales now seem to be eating sea otters instead of pinnipeds.
a lion.
Itself
Humans and human activity are the biggest threat to humans.