Sirens are enthralling creatures who lure victims to them through supernatural means. They lure these people to their doom, though not necessarily immediate death. In some versions their powers only work on men.
They have enthralling voices, while their appearance ranges from just very attractive when you've been out at sea for some time to a form of Glamour or out-and-out Mind Control. If they'll actually change their form to something ideally perfect for particular victims or at least project a vision of the same, they'll be a Shapeshifting Seducer. The method they typically also use is Mind Control Music.
They are at least humanoid, though the lower half is flexible. In Classical Mythology, sirens were bird-women, split about the same as a centaur. In most modern depictions of sirens the bird characteristics will be dropped and they'll be just beautiful women with beautiful voices, if they aren't mermaids, as bird-women nowadays are usually harpies.
In general (Greek): They were bird-women, they lured young sailors to their deaths via song that took them into rocky cliffs, there were between two and five, though three was common. Their names were a little... fluid.
In The Argonautica, the Argonauts also run into the Sirens. They survive thanks to Orpheus who sang an even more beautiful song that drowned out their call.
Teen Titans have a villain called Siren who is a mermaid with a hypnotic song and is capable of turning her tail into legs.
In the Soviet film Teens In The Universe, the evil robots invented The Call, a hypnotizing series of sounds that cause the aliens to lose control and dumbly follow it to their death, or “happiness” as the robots call it. The Call doesn't actually work on humans, though the robots have no way of knowing that.
A case of Maybe Magic, Maybe Mundane occurs in The Wicker Man. Willow dances naked in the room next to Howie's, slapping the wall between them and singing to him. The staunchly Christian Howie is literally trembling with desire, but doesn't succumb.
In the made-for-TV film Mermaids, one of the sisters Venus is also a Siren. She's able to hypnotise men with her eyes rather than her voice though if they know she is a Siren, she has no power over them.
A famous German poem by Heinrich Heine describes the Lorelei, a beautiful maiden who sat on a rock in the middle of the Rhine, singing and combing her hair, who lured sailors to their deaths. Set to music by Friedrich Silcher, it has become one of the most beloved German folk-songs.
The Percy Jackson series portrays sirens in a tweaked version of their Greek Mythology incarnation, as horrible giant condor-like creatures with long necks and the heads of women, faces dripping with the remains of their victims.
The title character of John Everson's Siren is a monster who is mostly similar to the original Greek myth. Her true form is that of a monster with both avian and piscine traits, but her song projects a glamour that makes her look like a beautiful woman in addition to entrancing humans, and she prefers to seduce the human men she preys on before eating them. She also answers to the name of Ligeia, and implies that she is one of the original Greek sirens.
The Syren in Septimus Heap uses her call to lure and strand Nicko and the Cerys onto Syren island.
In Cat Adams's Blood Singer series the sirens are human-looking semi-immortal women with telepathic abilities that let them control heterosexual men and also have a strong affinity for the ocean and aquatic creatures. It is stated that when calling out to males, some sirens focus their summons through music, but most use telepathy.
Piers Anthony's novel The Source Of Magic. The Siren is the sister of the Gorgon and has a half-human body. While playing her dulcimer, she can sing an entrancing song that causes males to travel to her location.
Live Action TV
The Psirens from Red Dwarf were basically a retelling of the sirens story IN SPACE!: they shapeshifted to lure spacecraft onto the asteroids.
On the 1960s Batman series, Joan Collins played the Supervillainess Lorelei Circe, AKA The Siren, who was able to put any man under her spell by singing a note of three octaves above high C; she used her ability to entrance Commissioner Gordon into sneaking into the Batcave, to cause Chief O'Hara to jump into a lake, and to induce Bruce Wayne into signing his fortune over to her.
One episode of So Weird dealt with a siren who looked like Jewel Staite and sang in a nightclub. Any man who heard her fell under her spell, while women thought her voice was pleasant but couldn't understand the fuss all the men were making over her.
The episode "Sirens" of The Legend Of Dick And Dom has the sirens as beautiful women with songs that draw in and possibly mind-control men- who promptly start trying to impress them with lies about being rich and fit- but sound like screeching to women. They imprison men and feed them up before eating them. The sirens also seem to have glamour; when they turn it off, they are still beautiful but have fangs and claws.
The Charmed episode "Siren Song" features a Siren as the Demon of the Week. According to the Book of Shadows she was a mortal woman who seduced a married man but was burned alive by the townspeople. Now she hypnotises married men with her song, which lures the wives to the scene of the crime where she burns them both alive.
H 2 O Just Add Water has the episode "The Siren Effect" where Cleo touches water at the full moon and gains a hypnotic singing voice that brings in every boy in town. She goes on the radio and wakes up the next morning to find hundreds of boys camped out on the front lawn to hear her sing.
SNL, did a spoof of The Odyssey where Odysseus(Jason Sudekis) has his men put beeswax in their ears and tie him to the mast to resist the Sirens(Christina Applegate, Kate Mc Kinnon and Cecily Strong) whose singing enchants sailors to crash against the rocks of their island. However they sing songs by female artists from The Nineties like Lisa Loeb, Paula Cole, Shania Twain, Sheryl Crowe and TLC which Odysseus can't help but love and sing along to:
The Sirens:(singing) I don't want to wait, for our lives to be over...
Odysseus: (singing) I want to know right now, what will it be! How do I know the words?! I only know manly sea-chants!"
Once Upon A Time has a siren as the guardian of a lake whose waters can heal any curse. She can change herself to look like anyone else, and drowns anyone that approaches the lake. Prince Charming manages to resist her charms, even after she makes herself look like Snow White, and kills her. Unfortunately, this eventually causes the lake to go dry.
Supernatural had a gorgeous female siren who worked as a stripper and convinced her clients to kill the woman closest to them, usually their wife or elderly, sick mother. She was revealed to be a hideous, melting fish thing whenever seen in a mirror. She also appeared as an attractive male FBI agent to Dean. Make of that what you will.
iamamiwhoami's entire premise is built around the concept of the siren song of a mandrake or mandragora. The title of preview video "18.104.22.168.22.214.171.124.18.1.1110" decodes to "mandragora", and the enchanting song aspect is most prominently in "b", "u-1", and "u-2".
The harpy is the Greek Mythologyversion (bird/woman) with an alluring voice that draws victims to its location.
The sirine is a humanoid female with a voice that can charm all hostile creatures.
The Golden Apple, another loose Americanization of The Odyssey, represents the sirens as a group of singers in a waterfront dive who sing "Goona-Goona." In this tale, Ulysses doesn't think to plug his men's ears, and most of them end up shanghaied.
In Final Fantasy VI, she is a summon that randomly silences all enemies or does minor damage with an ability called Lunatic Voice.
In Final Fantasy VIII, she is a summon who deals non-elemental damage and silences all enemies.
She appears in the Machinima adaptation The Sorceress War as Selphie's summon. Selphie summons her to fight the Elvoret in Dollet (the monster from whom she is Drawn in the game) and she seems to have powers more like a banshee as her voice deafens the monster long enough for Squall to kill it.
In Touhou, Mystia Lorelei isn't explicitly a siren but she's a bird-person who lures unsuspecting travelers to their deaths with a magic singing voice, so she's pretty obviously a siren. Although nowadays she's more likely to sell them food instead of eating them.
Uniquely, her song also causes night blindness. Anyone who hears it has no choice but to follow the sound of Mystia's voice or else wander in complete darkness. Mystia tells the unfortunate one that the night blindness can be cured by the food she sells, but in reality she just lifts the curse while the 'customer' eats. Mystia scams people like this very frequently.
Three sirens pop up in "The Scotsman Saves Jack", an episode of Samurai JackThe Scotsman doesn't demonstrate any particular willpower, he just doesn't like the music. They aren't bird-women or fish-people, they're fully human-looking...except forthe glow. And then we find out that they're a Scaled Up three-headed...thing. Still called sirens, though.
Apparently hydras and sirens decided to mingle over the years...
On The Simpsons "Tales from the Public Domain" when Homer was Odysseus he was lured to the Island of Sirens, only to discover that the Sirens in question were Patty and Selma. He got out of there pretty quick.
Make them the top of some kind of sea monster that lurches out when boats get close enough.
In the Hanna Barbera Godzilla, the Calico washes up on the shore of a cursed island ruled by a siren named Morphea and her two sisters. In addition to Mind Control powers, they also have a pet giant Chimera for Godzilla to fight.
One episode of American Dragon Jake Long features a mind-controlling siren as a villain, but she doesn't spend any time in or near the ocean. It also subverts expectations because the siren is a dowdy, geeky girl, not one of the hot cheerleaders that the characters had suspected.
Star Trek The Animated Series episode "The Lorelei Signal". A group of alien women send out a song over subspace radio once every 27 years to lure a starship to their planet. They must do this so they can drain the male crew members of their Life Force in order to survive.
An episode of Martin Mystery had the gang encounter a siren who attacks a nearby town out of anger after a relationship with a sailor turns sour. Unlike the myths, the siren could change between a beautiful lady and a bird monster at will.
The Bad Powers, Bad People trope is surprisingly averted by the Siren in Extreme Ghostbusters as she's one of the very few ghosts that actually care about the mortals she seduces with her singing voice. Her sister Banshee forces her into stealing the youth of her listeners to sustain her strength. She finally develops a backbone and rejects her sister when she coerces her to steal the remaining life force of her agefied audience (including Roland, who fell under her spell) and willingly allows herself and her sister to be captured and put into containment by the team.
In The Backyardigans episode "Sinbad Sails Alone", Tyrone and Pablo encounter Siren Uniqua when they travel to her island to get water. They then play a game of "Siren Says" with a mambo song to match.
"When I say 'Siren Says' you do Exactly whatever I told you to But if you do something Siren didn't say You gotta go back—that's how we play"
In an episode of Lloyd in Space there was an exchange student from the centre of the universe named Sirenia who was able to hypnotise all the boys, though with her eyes instead of her voice. The only way to break the spell was to get a boy from the same place to hypnotise her.