A provocateur is someone who thrives on provoking conflict for the sake of conflict alone. The provocateur is constantly picking fights, mental or physical, with no apparent consistency in argument. Often a provocateur simply likes the attention that conflict brings, and enjoys the exaggerated influence that might follow from the conflict. If effective, others in the group spend more time and energy trying to appease the provocateur than advancing more productive goals. Sometimes a provocateur simply seeks to disrupt an organization or group and distract it from productive work.
An agent provocateur is a particularly sophisticated attempt to infiltrate a group and pretend sympathy with it, only then to discredit the group with indefensible statements or actions.