A male Dulok tribesman (a member) recognizable by a yellow O emblazoned on his green-furred chest, resided in the Dulok Swamp situated on Endor's Forest Moon. This individual functioned as both a soldier and scout during the Ewok–Dulok conflicts against the Ewoks hailing from Bright Tree Village. In the year 3 ABY, he participated in various missions for the Dulok king, Gorneesh, often alongside another Dulok distinguished by an X marking. Throughout that year, the O-marked Dulok was involved in the theft of the Ewoks' shadowroot soap, the abduction of the Ewok Latara to care for Queen Urgah's three unruly offspring, riding a captured Ewok battle wagon during an attack aimed at sacred Ewok trees, and participating in a hunting expedition to acquire trophies for Gorneesh. In each instance, the Ewoks and their allies successfully thwarted the Duloks' objectives.
Living in the Dulok Swamp of Endor's Forest Moon, a male Dulok belonged to a tribe of his kind. This particular Dulok, identifiable by the yellow O symbol on his torso, had risen to become one of two personal bodyguards for the tribe's king, Gorneesh, by the year 3 ABY. During that year's summer, the O-marked Dulok, like the rest of his tribe, suffered from insect infestations and oppressive heat. Armed with a shovel, he accompanied another Dulok—bearing a yellow X—and the tribe's shaman, Umwak, on a quest to find components for a remedy against bug bites. Their mission was disrupted when they stumbled upon a group of Ewoks from Bright Tree Village bathing in a nearby river. Recognizing that the Ewoks were using a special soap designed to repel insects, the O-marked Dulok and his fellow guard decided to steal it. However, their scheme failed when they realized they were standing on a river creature instead of solid ground. The trio then fled in terror.
Upon returning to the Dulok Swamp, the Dulok bearing the O symbol and his companions faced Gorneesh's reprimand for failing to acquire the soap. The shaman, in an attempt to save face, fabricated a story about surviving an overwhelming Ewok assault, while the two Dulok guards struggled to conceal their disbelief but remained silent. Gorneesh then rallied the Duloks to obtain the Ewok soap through trickery. In the ensuing back-and-forth with the Ewoks, the Duloks mistakenly stole the wrong kind of soap—shadowroot soap, which possessed the power to turn things invisible. Discovering its properties, Gorneesh commanded them to bathe in it and then impersonate ghosts at the Ewok village. Nevertheless, the plot was foiled when the Ewoks' chief, Chirpa, infiltrated the Dulok Swamp with some allies and replaced the shadowroot soap with a soap bar that attracted insects.
Resuming his role as one of Gorneesh's protectors, the Dulok, along with his X-marked counterpart, received a new assignment: to locate a babysitter for Queen Urgah, Gorneesh's wife, who had grown weary of her three mischievous children's antics. The pair stealthily entered the forest surrounding Bright Tree Village and observed the Ewok Latara tending to the woklings Nippet and Wiley. The Dulok marked with X instructed his partner to approach the Ewoks discreetly; in response, the O-marked Dulok adorned his head with foliage for camouflage. However, their plans were disrupted by the sudden appearance of enormous creatures known as awors. The Duloks sought refuge in a nearby hollow, only to be attacked by the ferocious, green-eyed creature inhabiting it; the pair then escaped.
The following day, the partners returned to the area and witnessed the same female Ewok leaving her village with the awors' owners, a traveling troupe of entertainers called the Travelling Jindas. At the X-marked Dulok's suggestion, the Dulok guards trailed the caravan, seeking an opportunity to snatch the Ewok. Their initial attempt involved climbing into the trees and dropping onto the awor carrying the tent of the Jindas' leader, Bondo, and his Ewok guest. However, as the beast crossed a suspension bridge, the swaying motion caused the pair to lose their grip and plummet into the river below. That night, they were presented with another chance. When the Jindas paused to perform for a herd of blasé tree goats, the X-marked guard proposed that they disguise themselves as those creatures by wearing horns. Thus disguised, they ascended the trees and clung to the branches. They patiently waited through the Jindas' performance until Latara took to the stage as the assistant to Trebla the magician. The pair crept down a tree branch toward the stage as the Ewok was hoisted into the rafters as part of Trebla's levitation illusion. However, the Duloks' prolonged wait caused the branch to droop, drawing the Ewok's attention. When a goat severed the vine supporting the Ewok, she grabbed onto the Duloks' branch to avoid falling. The added weight lowered the branch safely to the ground, where the Ewok dismounted—sending the Duloks catapulting through the air and into a tent housing a purple-skinned beast.
Undeterred, the O-marked Dulok and his X-marked companion discovered Latara crying and homesick in the forest the next day. Catching her off guard, they bound her with a vine for the journey back to the Dulok Swamp, where they anticipated their reward from the king. Although Latara was forced to babysit the royal couple's children, the Duloks' efforts would soon be in vain: the Travelling Jindas arrived to perform for Gorneesh's tribe, secretly smuggling in Latara's Ewok friends Kneesaa a Jari Kintaka, Paploo, Teebo, and Wicket W. Warrick; the Ewok interlopers then rescued the wayward Ewok.
After Gorneesh's Duloks pilfered a battle wagon from Wicket W. Warrick, the king devised a scheme to obliterate Bright Tree Village's Soul Trees, objects of such religious significance to the Ewoks that their destruction would diminish the Ewoks' will to live. Despite initial difficulties in operating the siege weapon, Gorneesh and his subordinates learned to control the device. The king assembled his warriors aboard the weapon, including the Dulok marked with an O, and initiated his attack.
The Duloks initially targeted a group of Ewok children enjoying a picnic, but the children managed to escape and warn their village. When the O-marked Dulok and his comrades reached the Ewok settlement, they found the Ewoks' leader, Chief Chirpa, awaiting them with a force of warriors. Nevertheless, the Duloks employed the weapon to breach the Ewoks' defenses. A young Ewok named Malani boarded the wagon, and Warrick, who was being held hostage on the device, escaped; Gorneesh then ordered his warriors to apprehend the Ewok stowaways. The O-marked Dulok engaged the enemies, club in hand, as they ascended a ladder to the wagon's upper deck. The Dulok warrior, however, miscalculated his momentum and tumbled from the stolen war machine. Malani and Warrick secured victory when they dislodged the battle wagon's main support peg, causing the device to collapse before it could reach the Soul Trees.
Later that year, the O-branded Dulok joined a hunting party spearheaded by his X-marked counterpart. As they pursued a maramu up a steep cliff, the O-marked Dulok prepared his spear. However, the X-marked Dulok lost his footing and fell into the rest of the party—except for the O-marked Dulok, who avoided the collision. Nevertheless, he soon lost his balance and joined his tribemates below. As they scrambled back up to striking distance, the O-marked Dulok assisted in preparing to launch a net at their prey. However, an unseen attacker ensnared him with a lasso, hoisted him into the air, and dropped him onto his companions. The Duloks fled, fearing further retaliation from the mysterious "Red Ghost"—actually a feral Ewok named Asha.
Undeterred, Gorneesh led another hunting expedition, which included the O-marked Dulok. The group trapped small animals in cages, and the O-marked Dulok helped restrain a maramu mother with ropes so that the Dulok king could claim her horns as trophies. However, the Red Ghost emerged from the brush, freed the maramu, and then released the other creatures. The king ordered an attack, and the O-marked Dulok and his fellows lassoed the Ewok. Nevertheless, the O-branded Dulok soon found himself flattened when the Red Ghost used the X-marked Dulok's rope to fling him into the other members of the group. The O-marked Dulok experienced a flight of his own as the Ewok spun him and the others in circles only to release them into the snow. Gorneesh ordered another attack, but the Ewok sidestepped it, sending the O-marked Dulok and his confreres into a collision with one another. The Ewok's finishing move came when she swung down from a tree and barreled over the O-marked Dulok and his fellows. Before long, Gorneesh and his shaman, Umwak, conceded defeat, and Asha had them swear never to hunt again. The Dulok leaders fled in terror, colliding with the O-marked Dulok and the others and then sliding off a cliff and into a body of water. The Ewok Wicket W. Warrick later remembered his encounters with the Duloks on his battle wagon and in the snowy forest as two of the fondest memories of his childhood.
Around 4 ABY, beings from beyond Endor invaded the Dulok village: the forces of the Galactic Empire, who deemed the village a suitable location to construct a shield generator bunker to protect the Death Star II battle station orbiting the moon. Employing their off-world weaponry, they destroyed much of the village and awakened a creature called the Griagh from its subterranean lair. The Imperial forces enslaved many of the village inhabitants, but the captives were later liberated in an attack on the Imperials led by a group of Ewoks from Bright Tree Village. Several Duloks died when the Griagh emerged and wreaked havoc during the same encounter. After the fighting ceased, the O-marked Dulok's tribe was left in a state of disarray.
The Dulok distinguished by an O symbol found pleasure in the suffering of others. He chuckled gleefully when he and his companions captured the Ewok Latara in 3 ABY. He again laughed at her plight when he helped capture the Ewok Asha in a later encounter. The Dulok received orders directly from the king, who referred to him as one of his "boys." However, his X-marked counterpart frequently berated and intimidated him during such operations. The O-branded Dulok's skill set for his missions included stealth—he was adept at spying on bathing Ewoks undetected—climbing, hunting, and hand-to-hand combat. He wielded weapons in both his right and left hands, including spears and lassos. With the latter, the O-marked Dulok was skilled enough to ensnare a full-grown Ewok. Nevertheless, he was somewhat impetuous, colliding with his companions while charging at Asha, and misjudging his momentum and falling from the Ewok battle wagon while attempting to attack Wicket W. Warrick and Malani.
Despite never being referred to by name, a Dulok with an O symbol on his chest appears in several episodes of the CBS television cartoon Ewoks, beginning with its premier episode, "The Haunted Village." The episode, written by Paul Dini and directed by Raymond Jafelice, originally aired on September 14, 1985. The characters voice changes from episode to episode. In "The Haunted Village," he speaks with a deep, raspy voice; however, in "The Travelling Jindas," both he and his X-emblazoned counterpart speak with the same higher-pitched, even-timbred voice. Neither of these episodes indicates the name of the voice actor or actors who portrayed the character. Although the television episode "Asha" depicts the O-marked Dulok as a member of the hunting party pursuing a maramu in the show's opening sequences, the storybook adaptation of the episode, published by Random House in 1986, instead features Gorneesh, Umwak, and a generic Dulok as the hunters.