3. Pirates of the Caribbean 3 - Oh Snap, Kraken Got Popped
In Pirates of the Carribean: Dead Man's Chest, the big bad Kraken is controlled by the even more mythical Davy Jones, and after it is summoned it destroys everything in its path. As far as havoc-causing ocean-dwellers go, a mammoth tentacled creature that can destroy entire ships makes it probably the most fearsome thing in the Pirates franchise. But after it eats Jack Sparrow, it is destroyed by Jones somewhere between Dead Man's Chest and At World's End. This is referenced very briefly by a British commander and we briefly see the Kraken's corpse, but just how it was killed is not shown. This is a beast that had gun powder blown up on its limbs several times, essentially ate significant portions of several ships, and killed Jack Sparrow (albeit temporarily), and we are just supposed to accept that it was dispatched by Davy Jones quickly and easily? Just a bit of speculation, but I think the real reason behind the Kraken's demise is that they no longer needed it in the story, and they realized having a ten ton trump card in the hands of one of your villains makes the game a little unfair. So the Kraken went away, but it would have been pretty great to see just how you kill a seemingly unkillable fiend.