Siren (Supernatural)

Siren aka Nick Munroe was a Siren and also a main antagonist of the episode of Supernatural called Sex and Violence.

Supernatural
Before introducing herself as an FBI detective, she manipulated several men into killing their wives or girlfriends, thereby ruining their lives by getting them arrested. She also seduced a man and made him kill his own mother. When he introduced himself as an FBI detective as Nick Munroe's identity, he worked the same case with the Winchester and had a good relationship with Dean. And when Sam and Dean split up for a strip club to investigate the case with Nick. There Dean realizes that he's not as tight as the other feds.