Leviathan

The Leviathan is a monstrous Atlantean autonomous vehicle that guards the undersea entrance to Atlantis in Atlantis: The Lost Empire. Mirage summoned the creature in order to "destroy" Spongebob and his friends, but in reality, it was to safely bring Rourke and his shocktroopers to Atlantis so that they could sack its treasures. Currently, the Leviathan has been transformed into a Heartless by Maleficent for it's failure to stop our heroes.