General terms:
* Frightener: This is a straightforward and neutral term.
* Terrorizer: This implies a more intense level of fear and intimidation.
* Intimidator: This emphasizes the use of threats or power to instill fear.
* Threat: This is a term used to describe someone who poses a danger or risk.
More specific terms:
* Bogeyman: A mythical creature used to frighten children, but can also be used metaphorically for anyone who inspires fear.
* Boogeyman: Similar to bogeyman, but more common in American English.
* Scourge: This refers to someone or something that causes widespread suffering or destruction.
* Tyrant: A cruel and oppressive ruler who inspires fear and obedience through force.
* Monster: This refers to someone who is considered inhuman or monstrous in their actions.
Literary terms:
* Villain: This is a character in a story who opposes the protagonist and typically inspires fear or hatred.
* Antagonist: This is a more general term for any character who opposes the protagonist, but may not necessarily be inherently frightening.
The best word to use will depend on the specific situation and the type of fear being inspired.