Blackmailer (noun)

1. A person who extorts money or something else of value by threatening to reveal embarrassing, damaging, or compromising information about the victim.
2. A person who uses threats or other forms of coercion to obtain something, usually money, from another person.

Origin:

From black mail, from black "evil" + mail "rent, tribute".

Examples:

1. The blackmailer demanded money in exchange for keeping quiet about the victim's secret.
2. The police are searching for the blackmailer who has been extorting money from local business owners.
3. She was the victim of a ruthless blackmailer who threatened to reveal her past.
4. The blackmailer's threats caused a great deal of stress for his victims.
5. He was arrested for being a blackmailer who used to extort money from politicians.