Tiddalik

Tiddaliks are giant, drought-causing monstrosities resembling grossly swollen frogs. They travel through the land, sniffing out water to gorge themselves on. Upon finding a source, the tiddalik submerges itself and begins to drink, and drink, and drink. Over time, it slurps the water down to the very last drop and balloons in size, becoming unable to move at more than an amble. The water sustains the tiddalik for years, while the land suffers a great drought. In fact, the only moisture to be found in any quantity might be the damp divot the tiddalik's great, sloshing body leaves behind as it travels.

Desperate locals trying to undo a tiddalik's work are met with the creature's gullet or torrents of water. A tiddalik is lazy and unlikely to start a fight of its own volition or even to chase a fleeing attacker, having little interest in anything but slaking its immense thirst. In its death throes, the tiddalik divulges its water stores, breaking free in a final tide of mass destruction that swamps the surrounding area. Woe betide any unlucky enough to find themselves beset by a tiddalik's gluttony!