Arctic Leviathans were very tall, grey dragon-like monsters native to planet Grelbin. They dwelled in pits of freezing water which were frozen over, and when the Lombax approached them, they burst up through the ice and attacked him with an extremely cold beam of energy. Upon dying, the Leviathans fell back into the water and released moonstones. Ratchet retrieved several of these moonstones for the New Age Mystic on planet Grelbin, several of which were found in the Leviathans. Apparently the colonists of planet Grelbin created the genetic predators known as the Y.E.T.I.'s to exterminate these Arctic predators, but it appears to have backfired, now eating any travelers that set foot into the frozen tundras (including the Y.E.T.I.s themselves). It happens quite the opposite as leviathans eat the Y.E.T.I.s (Ratchet can see that on a distance from the leviathan).
- There are only 33 Arctic Leviathans in the entire game, and after killing them all they cannot be found again, unless the player start challenge mode, or a new game.
- There is a glitch in Ratchet & Clank: Going Commando in which should the player activate the Weapons Quick Select when the Leviathan charges its beam, it would make the Leviathan keep on charging the attack, making the energy ball bigger and bigger until the player resumes game.
- Ratchet & Clank: Going Commando (first appearance)