|This article relies on references to primary sources. (April 2013)|
The Pequod is a fictitious 19th century Nantucket whaleship that appears in the 1851 novel Moby-Dick by American author Herman Melville. The Pequod and her crew, commanded by Captain Ahab, are central to the story, which, after the initial chapters, takes place almost entirely aboard the ship during a long three-year whaling expedition in the Atlantic, Indian and South Pacific oceans. Most of the characters in the novel are part of the Pequod's crew, including the narrator Ishmael.
The ship is first encountered by Ishmael after he arrives in Nantucket and learns of three ships that are about to leave on three-year cruises. Tasked by his new friend the Polynesian harpooner Queequeg - or more precisely, Queequeg's idol-god, Yojo - to make the selection for them both, Ishmael, a self-described "green hand at whaling" goes to the Straight Wharf and chooses the Pequod.
It is revealed that the Pequod was named for the Algonquian-speaking Pequot tribe of Native Americans who once inhabited New England along Long Island Sound during the 17th century, but were annihilated during the Pequot War and are "now extinct as the ancient Medes". The reference to the doomed tribe is a deliberate foreshadowing of the fate of the ship and her crew.
The Pequod has endured the years and the elements, but not without sustaining damage. The ship is three-masted, like most Nantucket whalers of the time, but all three masts are replacements, taken on when the originals were lost in a typhoon off Japan.
The Pequod is not unlike Ahab in this respect, since many of the rest of these missing elements have been replaced by the bones of the whales she hunts. She is not a new vessel, and with age would usually come some veneration and respect, which Ishmael tries to convey by using several historical references in his description of her. But in the Pequod's case this has been negated by the thick veneer of barbarity that has been overlayed onto the ship in the form of fantastic scrimshaw embellishment. Far from enjoying mere utilitarian replacements out of available whalebone, she has been ornately decorated, even to the whale teeth set into the railing that now resemble an open jaw. Like a fingerbone necklace on a cannibal, these adornments are clear evidence of the Pequod's prowess as a successful hunter and killer of whales.
... a rare old craft...She was a ship of the old school, rather small if anything; with an old fashioned claw-footed look about her. Long seasoned and weather-stained in the typhoons and calms of all four oceans, her old hull's complexion was darkened like a French grenadier's, who has alike fought in Egypt and Siberia. Her venerable bows looked bearded. Her masts...stood stiffly up like the spines of the three old kings of Cologne. Her ancient decks were worn and wrinkled, like the pilgrim-worshipped flag-stone in Canterbury Cathedral where Beckett bled. But to all these her old antiquities, were added new and marvellous features, pertaining to the wild business that for more than half a century she had followed...She was apparelled like any barbaric Ethiopian emperor, his neck heavy with pendants of polished ivory. She was a thing of trophies. A cannibal of a craft, tricking herself forth in the chased bones of her enemies. All round, her unpanelled, open bulwarks were garnished like one continuous jaw, with the long sharp teeth of the Sperm Whale, inserted there for pins, to fasten her old hempen thews and tendons to. Those thews ran not through base blocks of land wood, but deftly travelled over sheaves of sea-ivory. Scorning a turnstile wheel at her reverend helm, she sported there a tiller; and that tiller was in one mass, curiously carved from the long narrow lower jaw of her hereditary foe...A noble craft, but somehow a most melancholy! All noble things are touched with that.—Moby-Dick, Ch. 16 
The principal owners of the vessel are two well-to-do Quaker retired whaling captains, therefore "the other and more inconsiderable and scattered owners, left nearly the whole management of the ship's affairs to these two."
Captain Bildad, who along with Captain Peleg was one of the largest owners of the vessel; the other shares, as is sometimes the case in these ports, being held by a crowd of old annuitants; widows, fatherless children, and chancery wards; each owning about the value of a timber head, or a foot of plank, or a nail or two in the ship. People in Nantucket invest their money in whaling vessels, the same way that you do yours in approved state stocks bringing in good interest..—Moby-Dick, Ch. 16 
Peleg served as first mate under Ahab on the Pequod before obtaining his own command, and is responsible for all her whalebone embellishments.
...during the term of his chief-mateship, [he] had built upon her original grotesqueness, and inlaid it, all over, with a quaintness both of material and device, unmatched by anything except it be Thorkill-Hake's carved buckler or bedstead...—Moby-Dick, Ch. 16 
The depiction of life aboard the ship, although fictionalized, was based on Melville's own experiences in whaling (specifically aboard the Achushnet in the 1840s) and thus can be taken in many ways as representative of mid-19th century Nantucket whaling.
The Pequod is initially described as having by a tiller made from a whale's lower jaw, yet in one instance the helm is described as having "spokes", which refers to a wheel. (Interestingly, both of the movie versions retain this anomaly, showing both steering elements aboard the same ship).
During the most violent shocks of the Typhoon, the man at the Pequod's jaw-bone tiller had several times been reelingly hurled to the deck by its spasmodic motions, even though preventer tackles had been attached to it - for they were slack - because some play to the tiller was indispensable.—Moby-Dick, Ch. 123
"Clear away the boats! Luff!" cried Ahab. And obeying his own order, he dashed the helm down before the helmsman could handle the spokes.—Moby-Dick, Ch. 61
...every day when Ahab, coming from his cabin, cast his eyes aloft, the vigilant helmsman would ostentatiously handle his spokes...—Moby-Dick, Ch. 118
Cultural references 
In Stephen King's book, The Stand, it is noted early in the story that the full name of the character Glen Bateman is "Glendon Pequod Bateman," possibly in reference to either the ship or the Pequot tribe.