Kraken

The Kraken was an enormous sea creature, said to be the length of ten ships, closely resembling a giant squid. The Kraken was the subject of many legends that circulated for centuries on the high seas.

Background Information
The Kraken was controlled by Davy Jones, ruler of the sea, and commanded to prey upon ships to ensure Jones had many unwilling candidates for service aboard his vessel, the Flying Dutchman. The Kraken could be summoned from aboard the Flying Dutchman, with the use of a giant hammer that sent a shock wave through the ocean that served as a call to the creature. Jones would recite a chant while his crew summoned the beast. The Kraken was unleashed upon those who had been marked with a Black Spot, and could only be called off if Jones himself removed the mark. A person given the Black Spot would be ruthlessly tracked by the Flying Dutchman and the Kraken, and even items of clothing or personal belongings left by the target would attract the creature on its hunt. Davy Jones was further able to order the Kraken to attack specific ships, as he did against the Black Pearl off Isla Cruces.

Role in Dead Man's Chest
Captain Jack Sparrow was given a Black Spot by Bootstrap Bill Turner, on behalf of Davy Jones, and was forced to avoid the open water to escape the Kraken. Ultimately, however, he was forced into a confrontation with the beast, and was consumed by it aboard his ship, the Black Pearl. Witnessing this, Jones stated that Sparrow's debt was paid.

Role in ''At World's End
Shortly after obtaining Davy Jones' heart, Cutler Beckett ordered Jones to kill the Kraken, knowing that it was too dangerous and unpredictable to be allowed to live. Upon returning from Davy Jones' Locker, Jack Sparrow and his companions discovered the dead beast washed up on a beach. Pintel and Ragetti approached the Kraken's face, Pintel poked it with a long stick. They mused on calling themselves "Kraken Slayers" and turning the creature into an exhibit. Sparrow reflected on his own mortality while looking into the beast's glazed eye. It is unknown how Jones killed the Kraken.