provocateur
One who engages in provocative behavior.
Near-synonyms: provoker (sometimes synonymous), agitator
An undercover agent who incites suspected persons to partake in or commit criminal acts.
Near-synonyms: agitator, inciter
Where it comes from
Borrowed from French provocateur. Doublet of provocator.
Adapted from the Wiktionary entry provocateur (CC BY-SA 4.0).