Davy Jones is a fictional character in the Pirates of the Caribbean series. He appears as a secondary antagonist of Dead Man's Chest and main antagonist of At World's End. Davy Jones is the captain of the Flying Dutchman (based on the feared ghost ship of the same name featured in nautical lore), roaming the seas in search of souls to serve upon his vessel for a century. In the story, his original purpose was to carry souls of those who died at sea from this world to the next on his vessel. He was charged with this duty by his one true love, a sea goddess named Calypso. For every ten years at sea he could spend one day on land to be with her.
Davy Jones' physique was designed by the films' producers to be a mixture of various aquatic flora and fauna features. Jones' most striking feature is his cephalopod-like head, with octopus-like tentacles giving the illusion of a thick beard. The major features of the Davy Jones' physique bear strong resemblance to the mythical creature/god Cthulhu created by H.P. Lovecraft.
Source: Wikipedia, "Davy Jones (Pirates of the Caribbean)", available under the CC-BY-SA License.