User blog comment:ImperiexSeed/Supernatural Mysteries/@comment-3481504-20121103210705/@comment-5060540-20121103211423

Leviathans were created before angels and even archangels and had the power to consume everything, including angels. Castiel, a Seraphim, was terrified of their presence and even Eve, a distant relation to the Leviathans, knew how an angel ticked so why couldn't the Leviathans who predate even Eve. On the other hand, Archangels were created to be God's most celestial beings with power surpassing any angel along with any pagan gods. I don't know if the Leviathans knew about Archangels but considering their age, I would say they did. My answer is this: A weaker Leviathan could be killed by an Archangel with some effort, but a top-tier Leviathan could slaughter an Archangel.