Hades and his underworld qualify, as they are often portrayed as horrifying, ghastly, and generally evil. In reality, the Greek underworld, Erebos, is more like a pleasant inn, and Hades was just a little emotionally unstable. The only commonly-found no-no he did in mythology was kidnapping Persephone, and even then, some variations have Zeus selling her to him.
This tends to go for the other gods as well. Zeus is often thought of only as the god who went around having sex with women. Never mind he often punished evil doers or helped maintain the world. This is true for the other gods who had their petty moments, but were not evil or went around smiting humans for no reason. They usually had a reason even if only slight. They also had moments where they would help people who were beneficial to civilization.