Eugène-François Vidocq was a French criminal turned criminalist, whose life story inspired several writers, including Victor Hugo, Edgar Allan Poe, and Honoré de Balzac. He was the founder and first director of France's first criminal investigative agency, the Sûreté Nationale, as well as the head of the first known private detective agency. Vidocq is considered to be the father of modern criminology and of the French national police force. He is also regarded as the first private detective.

A private investigator, a private detective, or inquiry agent is a person who can be hired by individuals or groups to undertake investigatory law services. Private investigators often work for attorneys in civil and criminal cases.