Hailing from Yorkshire, England, the grindylow is vaguely humanoid with horribly long arms and fingers. Living in deep marshes, it waits for unwary children to wander by and pulls them into the water, drowning and eating them. It was sometimes a scaled, fishlike creature, but other times it had fur. The grindylow also sometimes preys on adults as well, but not as often as it eats children (Rose 155-156).
With its tendency to eat children who are too careless along the waterside, the grindylow fits into a nursery tale to keep children careful around water. However, the adult-killing variant of the grindylow also may have explained drownings when someone should really have known better.