A person who’s redoubtable is a person who inspires fear in other people.

We often find that quality in fiction to describe the antagonist of the story : the bad guy who’s redoubtable that everyone is scared of and who doesn’t hesitate to use violence to get what they want.

Being redoubtable means inspiring fear and dread and being cruel and fierce (see fierce). Some enjoy being scary because it’s a way to dominate others (see obedience).

Someone can be redoubtable when people ignore who they really are and what they are capable of. We only know that they are dangerous.