Abuser (noun)

A person who mistreats someone or something, especially by using them excessively or improperly.

Origin:

From abuse (verb).

Examples:

1. He was arrested for being an abuser of drugs.
2. She was a victim of domestic abuse by her partner, an abuser.
3. The abuser was finally brought to justice.
4. The abuser had a history of violence.
5. The abuser should be held responsible for their actions.