So: imagine an amphibian, about 4 -6 feet in length, with beady eyes, tiny fetus-like fingers, and a gaping maw that opens far enough to wrap around the forearm of a full grown man. Sound a little nightmare-ish? Here's some photos...
Both of the above are pulled off of Loren Coleman's Cryptomundo site, but there's nothing secretive about these guys. The Chinese and Japanese giant salamanders are well documented, if bizarre looking, inhabitants of Asian waterways.
Mostly gentle giants, they do have some ferocious teeth, and will bite if handled improperly or if snatched out of a resting place, as seen in this still from the terrific show River Monsters:
And here's a close-up of the teeth of the North American Giant Salamander, maxes out around 2 feet in length. (Photo from the University of Washington Archive):