The Siren (actual name unknown) is an antagonist appearing on the WB/CW television series Charmed, serving as the main antagonist of the Season 5 episode "Siren's Song."
The Siren was originally a mortal woman who fell in love with a married man and began an affair with him, only to be burned at the stake when the illicit relationship was discovered. She turned into a demon who targets couples, seducing the men with her magical song before killing them with a deadly kiss that utilizes the very flames that consumed her.
The Siren is first seen enthralling a man with her song when the man's fiancé, Melissa, enters the bedroom. She then kills the man and advances on Melissa, whom she knocks unconscious before setting fire to the bedroom. Unfortunately for the Siren, Melissa is saved by Cole Turner in an attempt to impress his ex-wife Phoebe Halliwell. It soon turns out that Melissa is a future Whitelighter.
The Siren is next seen in a bar, where she's about to seduce a guy when she sees a news report telling of Melissa's rescue by Cole; she then abruptly leaves. She goes to the hospital and teleports into Melissa's room just as Leo Wyatt enters and stops her. The Siren, seeing Leo's wedding ring, then enthralls Leo with her song and engages him in a passionate kiss. Piper and Paige interrupt the two, and Piper attempts to destroy the Siren, but fails due to her unborn baby altering her combustion power. The Siren then sends Piper falling out of the window, but ends up stabbed through the stomach; she then teleports away.
The Siren's wound is treated by a demonic healer, and she becomes bent on vengeance against the Charmed Ones. Later, when Cole interrogates the healer, the Siren enters and brings Cole under her thrall, kissing him. Sometime after that, the Siren is making out with a shirtless Cole on her bed when Phoebe, sensing the Siren's song, arrives; she then apparently kills Cole with her fiery kiss. Once Cole is down, she turns on Phoebe, who attempts to vanquish her with a potion that is then destroyed by a very-much-alive Cole, much to the Siren's shock.
Cole says he wants the Siren all to himself, and the Siren attempts to teleport away, only for Cole to grab hold of her before she can. Cole then starts to strangle Phoebe, and the Siren watches with a smile. Leo and Piper arrive, and Leo, temporarily possessing Piper's combustion power, tries to kill the Siren before finally succeeding.