Blackmailer
/ˈblækmeɪlər/
Definition 1 of 1
Pro Tip 1/3Negative Connotation
The term 'blackmailer' carries a negative moral judgment and implies criminal activity. 
The politician was ruined after being exposed as a blackmailer.
Pro Tip 2/3Emotional Impact
Victims or subjects of a blackmailer may experience fear, shame, or anger. 
He felt a surge of panic upon receiving the blackmailer's latest demands.
Pro Tip 3/3Secrecy Element
'Blackmailer' implies the use of secrets or private information as leverage. 
The blackmailer knew things about her past she thought were hidden.