A word/phrase for something that is outwardly fearsome, but in reality is nothing to worry about

I'm trying to think of a word or phrase that refers to something that appears dangerous or intimidating but is actually insignificant. "Ostentatious" seems to go in the right direction, (in the sense that it means "showy") but it doesn't have the connotations of "menacing". Is there such a word?

EDIT: Perhaps I should clarify; I was thinking more of occurrences that caused panic but in reality had little effect (eg. the Three Mile Island accident -- it was widely reported to be a horrific disaster, but it didn't release enough radioactive material to be linked to any cases of cancer.) In this question, I'm referring to the occurrence having earned a false reputation for being dangerous or fearsome.

Solution 1:

One idiom that comes to mind is "not as black as it is painted":

if people or situations are not as black as they are painted, they are not as bad as people say they are