Is kidnapper a common noun or a proper noun?

The Word kidnapper is a common noun, a Word for any kidnapper anywhere.

A proper noun is the name of a specific person, place, thing, or a title; for example:

• Bruno Richard Hauptmann, convicted kidnapper of Lindbergh baby.
• Cape Kidnappers, New Zealand
• Kidnappers Lane, Cheltenham, UK
• "The Little Kidnappers", 1953 movie with Jon Whiteley