B/X Monsters A to Z: Elephant
Real-world creatures statted up for D&D are almost always illuminating and confounding examples, and the elephant, from the Expert Rules, is no exception. Elephants are given an Armor Class of 5, equivalent to mail armor. That seems pretty stout, but the term "pachyderm," a common synonym for these largest of land animals, literally means "thick skin." I have never actually touched an elephant, much less tried to pierce its hide, (or mail armor, for that matter) but that AC 5 at least has the air of plausibility. Hit Dice-wise, the elephant has 9, which makes it equal to a blue dragon in its capacity to absorb physical punishment. It also makes it equal to a Name-level human fighter with no Constitution adjustments, and even a bit inferior to one with high CON, the realization of which has always made my brain itch; it just doesn't seem right for a 175-ish-pound human to be as tough as a giant beast weighing at least several tons. That's the abstraction...