There is only one great creature of note in 1958's Hercules. It's a massive dragon that Jason must battle in order to reach the Golden Fleece.
The creature is a "guy in a rubber suit" and it's not terrifically realized but I've seen worse! I actually quite like creatures who are played by people in suits. If they're shot correctly it can be really effective. At the very least you can tell it's really there and there's no digital-looking CG!