Giant frog

From Ardrana

Giant frogs resemble their more common relatives in everything but size. Their enormous size means that they consider larger creatures as a source of food, making small creatures and even demihumans possible prey. A giant frog can range from 2 to 6 feet in length and weigh between 50 and 250 pounds.

Note: Giant frogs originally appeared in this form in the 2nd Edition Monstrous Manual for the AD&D game from TSR. Their use here is for the purposes of providing context for the campaign only.