I had no idea that frogs could be so terrifying

Giant bullfrogs are frightening:
The giant bullfrog is like Kermit on steroids. When it lunges — and South African frog expert Vincent Carruthers has seen it attack horses — it's a fearsome sight, squinting and baring the two fang-like front teeth in its gaping, shovel-like jaw.

Right now one giant bullfrog, slightly smaller than a dinner plate, is busily trying to mate with a female perhaps a tenth his size. But before the deed can be consummated, another male swaggers up and launches himself in toothy-jawed attack.

Orange limbs fly and bullfrog No. 1 almost loses his lady, but manages to clamber back on. Again his rival attacks. And again. And again.
If you want to spice up your nightmares, here's videos of frogs eating mice:




*Buy B.P.R.D. Volume 12: War on Frogs at Amazon.