An agent provocateur (French for 'inciting agent') is a person who actively entices, encourages and incites another person to commit a crime that would not otherwise have been committed and then reports the person to the authorities. They may target individuals or groups.

In jurisdictions in which conspiracy is a serious crime in itself, it can be sufficient for the agent provocateur to entrap the target into discussing and planning an illegal act. It is not necessary for the illegal act to be carried out or even prepared.

Prevention of infiltration by agents provocateurs is part of the duty of demonstration marshals, also called stewards, deployed by organizers of large or controversial assemblies.

While the practice was worldwide in antiquity, modern undercover operations were scaled up in France by Eugène François Vidocq in the early 19th century, and included the use of unlawful tactics against opponents. Later in the same century, police targets included union activists who came to fear plain-clothed policemen. The French term agent provocateur was then borrowed as-is into English and German. In accordance with French grammar, the correct plural form of the term is agents provocateurs.

An agent provocateur is an individual who is recruited to infiltrate a group to incite others to commit illegal, rash or violent acts. The primary purpose is often to compromise the target group, justify actions against them or to discredit their causes.

Often, an agent provocateur gains the trust of a target organization (such as political movements, labor strikes or protest groups) to operate from within. Instead of observing or spying, the agent actively encourages and incite others to break the law. The evidence gathered from the illegal acts are then used by those who employed the agent to make arrests, prosecute members, justify repression or turn public opinion against the entire organization.

A political organization or government (domestic or foreign) may use agents provocateurs against their targets (political opponents (e.g. protesters), groups or nation states). The provocateurs try to incite their targets to do counter-productive, unpopular or ineffective acts, such as violence (arson, rioting, or bombing) to foster public disdain in order to destroy their reputation and/or provide a pretext for the final assault against the opponent. They engineer scenarios where a crime is committed, exploiting the group's willingness to act, which might not have occurred without the agent's involvement. They also aim to cause internal suspicion, paranoia, and dysfunction to split their targets, weakening it and making it easier for their opponents to manage or defeat it, often by influencing the direction and messaging that ultimately breaks the law.

Historically, labor spies, hired to infiltrate, monitor, disrupt, or subvert union activities, have used agent provocateur tactics.