Sirens (Pirates of the Caribbean)

"Anyway, about these Sirens...I don't know why I didn't realize it before. We've all heard the stories, the legends. Every sailor lives in fear of being called to their watery grave by the Siren's song. I guess I thought they'd be a bit more on key."

- Jack Sparrow to the crew of the Barnacle

Sirens were a legendary aquatic species who lived on Isla Sirena in Davy Jones' Locker. They used the merfolk and other species as intermediaries with sailors whom the Sirens attempted to lure to their deaths.

History
"So, it has recently become clear to me that the Sirens, or something like them, are the reason for all of this bizarre, strange and utterly unacceptable behavior."

- Jack Sparrow to the crew of the Barnacle By the time Captain Jack Sparrow began sailing with his first crew aboard the Barnacle, legends of the Sirens were already well known in the Caribbean. During the quest for the Sword of Cortés, the shipmates were accosted by the merfolk, who attempted to lure Sparrow's crew down to Isla Sirena, and from there deliver them to the Sirens. Jack, however, was able to bargain with the mermaids, first securing the safety of his crew, and, during his second visit to the island, winning his own freedom. Some time later, he personally encountered the Sirens, thought that story is still shrouded in mystery.

Society and culture
"Listen to us! We must be drunker than usual, mon ami! Talking seriously of magic! Next thing you know, we’ll be discussing making love to sirens and mermaids!"

- Christophe-Julien de Rapièr to Jack Sparrow Sirens were creatures whom sailors came to fear, depicted in legends as beings who lured men to a watery grave with their haunting song. In reality, they played a somewhat passive role, using agents such as the merfolk, gill men and sea warriors to do their bidding. In return, these lesser species were afforded the protection of the Sirens. Their agents were tasked with opening a sailor's heart to their deepest desire, until it became irresistible. At that point, the proxies would drag such doomed souls to a meeting with the Sirens themselves.