Gargantos

For most of the chase through New York, nobody can see Gargantos. The creature moves through the streets invisible to the human eye, so that cars crumple and a bus is hauled off the road with nothing apparently touching them, until a revealing spell strips the cloak away and leaves an enormous cephalopod standing in the open. It is strong enough to throw the bus and to hurl a motorcycle after a target it cannot reach, it climbs the sides of buildings on its tentacles, and it watches everything through a single great eye.