(From 5th Edition Monster Manual - 2014):

Cyclopes are one-eyed giants that eke out a meager existence in wild lands. Isolationists by nature, they avoid contact with other races and try to drive away strangers in their territory.

Nonreligious. Legends claim that the cyclopes are the spawn of one of the gods of the giants, but these creatures pay little heed to any deities. They see little benefit in prayer and dislike ritual, which they perceive as complex and foreign. However, a cyclops that gains direct benefit from some site of divine power, or which is threatened by a supernatural force or creature, will pay homage as long as the benefit or threat remains.

Unsophisticated. Though they are reasonably intelligent, cyclopes live simple, reclusive lives, keeping herds of animals for food. They prefer to dwell alone or in small family groups, lairing in caves, ruins, or rough structures of dry stone construction they build themselves. A cyclops keeps its herd animals with it at night, sealing the entrance to its home with boulders to let it serve double duty as a barn.

A cyclops lairs within a day’s journey of other cyclopes, so that they can meet to trade goods or seek mates. They craft weapons and tools of wood and stone, but will use metal when they can find it. Although cyclopes understand the Giant tongue, they write nothing and speak little, using grunts and gestures for their interactions with each other.

Cyclopes don’t use money for trade, but they value gold, shells, and other glittering and colorful objects as jewelry. A cyclops might wear a necklace strung with feathers and silver coins, but also with pewter goblets, cutlery, and other bits of ruined metal.

Unwise. Cyclopes aren’t great thinkers or strategists. Slow to learn and bound to their traditional ways, they find innovation difficult. Although they are a terrifying threat in combat due to their size and strength, they can often be tricked by clever foes.

Cyclopes can be cowed and awed by obvious displays of magic. Rustics with little exposure to magic, they can be deceived into mistaking a warlock, cleric, or other caster for a powerful divine figure. However, their sense of pride causes them to react with vengeful, bloodthirsty violence once they learn that the individual they assumed was a “god” is a mere mortal.

(From Bigby's Glory of the Giants - 2023):

Cyclopes. Contradictory legends explain the origin of cyclopes, and none of those legends are told by cyclopes themselves (who generally display little interest in the question of their origins and their connection to the gods). Some myths lump them in with ogres as descendants of Vaprak, while others claim they were once ogres who joined the ancient fomorians’ invasion of the Feywild and thus shared in fomorians’ banishment to the Underdark and the resulting corruption of their physical forms. One myth suggests cyclopes are descendants of Karontor like the fomorians, but stemming from a line that began after Karontor’s banishment rather than before it.

(By Eric Cagle in Dragon Magazine #323):

Legends speak of an enigmatic race of giants known as the cyclopes. Similar to hill giants in many ways, these brutes had one unique trait: single eyes situated in the middle of their foreheads. Cyclopes lived in an uneasy peace with other giants, with the one-eyed beings losing battles more often than winning. Over time, cyclopes lost the majority of their territory, forcing them to move farther into the wilderness or closer to the settlements of humanoid races, particularly humans. In most of these collisions of cultures, the humanoids treated cyclopes with fear and suspicion, resulting in the slow decline of the cyclopes population. Over the centuries, as the cyclopes died off, other races came to regard them as nothing more than a myth.

However, pockets of these giants survived in the wilderness and along the rocky crags of forbidding shores. Tales persisted of sailors running afoul of cyclopes living on isolated islands. Most of these stories ended poorly for the sailors, but some tell of a cyclops who would trade a glimpse into the future for goods or favors. In one story, a flood of refugees fled their city during a siege and sought out the ancient cyclops, Menta the Wizened. Menta foretold of great doom and despair for many of the refugees, but eventual revenge against their attackers. His prophecy came true, and the grateful survivors deified Menta and made his home a sacred place.

Worshippers and omen seekers often visited the island, and Menta took some as mates. His children, although smaller and weaker than the giant who begat them, slowly spread throughout the land and became a viable race in their own right. These first cyclopeans retained both their ancestor's ability to look into another person's future, as well as a deep passion for solitude and respect for nature. Most of these cyclopeans stayed close to the sea, doing their best to remain hidden from others. They made peaceful contact with gnomes, fey, and the rare dwarven clans who regarded cyclopeans with curiosity.

Although most cyclopeans consider Menta the father of their race, other myths persist that tell of tribes that descended from other cyclopes. Known as the feral-kind, these cyclopeans are violent and savage, like many other types of giants. While most cyclopeans descended from Menta wish only to live in peace, their brethren make life difficult for the race, attacking innocent travelers who roam too close to their caves and hovels.

Today, the two cyclopean branches form a minor, fragmented race, eking out an existence among more numerous humanoids. Rumors persist that some cyclopeans see visions of their race's ultimate fate - but none, even under pain of death, reveal what the future holds for their kind. Some sages speculate that the cyclopeans face a slow, agonizing extinction as their bloodline runs dry, although hints abound of the race gaining greater glory and respect.

Optimistic - some say naive - cyclopean adventurers dedicate themselves to increasing their race's beleaguered status. The boldest make quests to locate the few remaining cyclopes in hope of bringing power to their ailing race. The most fervent even believe Menta lives and waits for his children to return to him, and they scour the world seeking him.

Personality: Introspective and thoughtful, Menta cyclopeans often take a long-term view. Because of their ability to look into the future, cyclopeans often seem lost in thought, spending more time "looking forward" than paying attention to the world of the present. Even if not actively using their future sight, most cyclopeans spend their time mulling over other creatures' fates and what those creatures mean in the scheme of the universe. To others, a cyclopean might seem distracted and absent-minded, and often needs coaxing to pay attention to matters at hand. Otherwise, the relatively peaceful and withdrawn cyclopeans strive to live in harmony with their surroundings. Often witnesses to the folly in others, they maintain a fatalistic attitude toward life that makes them stoic and unemotional. They know of the future's eternal flux and that patience and calm help them survive turbulent times - they believe that if one waits long enough, new possibilities always emerge.

Their unique ability to see into the future creates two distinct personality types among the peaceful Menta cyclopeans. One type becomes deeply intrigued - almost obsessed - with the lives of other sentient beings, peering into the future and watching as their fates play out. Sometimes these cyclopeans befriend beings they see as having interesting fates, guiding those creatures with advice bestowed by their ability. The other type of Menta cyclopean, haunted and overwhelmed by seeing the fate of others, withdraws from society and seeks solitude. They reveal their secrets only through bribes, coercion, or methods of convincing them of the importance of their information.

Either way, many beings seek out cyclopeans in hope of finding out what the future holds. Most Menta cyclopeans loathe revealing too much and become angry or morose if asked too often. Menta cyclopeans cherish those beings who learn to accept them for more than their ability to see into the future.

Bitter and savage, the feral-kind cyclopeans use their great strength and physical prowess to toy with victims before killing them out of spite. These evil loners typically live close to other humanoids in order to have plenty of "toys" to play with. Feral-kind cyclopeans possess a dark and twisted view of the world, seeing it as a place of hardship where only the strong survive. They see their more peaceful brethren as weak and soft, misusing their talents and heritage for pointless reasons. Smarter feral-kind cyclopeans might even adopt the ruse of acting like their more gentle brethren in order to lure the naive and overly trusting.

Physical Description: Descended from the giant race of cyclopes, these extremely tall humanoids stand just shy of Large size at 7 to 8 feet. With wiry builds and ruddy, leathery skin, cyclopeans weigh between 250 and 350 pounds. Both types of cyclopean females generally wear their hair very long while the males shave their heads bald. Elder male cyclopeans commonly tattoo their smoothly shaved heads with intricate abstract patterns. The higher the male's status, the more complicated the tattoo.

Located immediately above the bridge of its nose, the cyclopean's single eye is slightly larger than normal for a humanoid of its size, and it requires far less blinking to keep it moist and safe. Its eye always has a brilliant color resembling a gemstone, with no two cyclopean irises sharing the same color. Because of their single eye, cyclopeans lack depth perception and few make use of ranged weapons, preferring to hunt with spears and clubs, or to fish for their meal. This lack of depth perception often causes them to ignore personal space and move uncomfortably close to others, and it also makes them nervous when people try to talk to them from far away.

Menta cyclopeans prefer to wear simple garb, such as tunics, loincloths, or robes, which they often wear short in the dry, arid regions that they commonly inhabit. They dislike bold and gaudy adornment, although almost every Menta cyclopean wears a necklace or other bit of tasteful jewelry made from natural materials. Feral-kind cyclopeans wear animal skins and bits of jagged metal, often culled from discarded or stolen armor.

Relations: Cyclopeans live close to the land, and as a result, find themselves dealing most often with gnomes, dwarves, and sylvan beings. Menta cyclopeans respect the privacy and territory of other races and ask only the same in kind. However, due to their future sight, other beings often seek out cyclopeans in hopes of having their futures predicted. Some tribes see little problem with this, trading information from their visions for goods from other races. Other tribes dislike the requests and demands of seekers who ask too much or too often, and they turn their backs on anyone who gets too pushy.

Feral-kind cyclopeans, particularly those who live deep in the wilderness, often find themselves dwelling side-by-side with sylvan races, such as satyrs, pixies, and dryads. Occasionally, this close proximity leads to violence, but the feral-kind cyclopeans have lost enough warriors in the past that they rarely start fights anymore. Most cyclopeans treat giants with a neutral attitude, knowing that they share a common ancestry but one they often wish to leave in the past. In turn, giants, especially hill and stone giants, regard cyclopeans with superstition and begrudging respect. Most giants simply leave them alone, sensing the blood of the cyclopes running in their veins. The more enlightened and intelligent giants, such as cloud and storm giants, have a patronizing view of cyclopeans, seeing them as a failed and dying bloodline doomed to pass into obscurity.

The two cyclopean factions do not get along, their meetings often ending in bloodshed. However, because their race lacks numbers, few cyclopeans actively quarrel with their kin. At best, Menta and feral-kind cyclopeans simply ignore each other and strive to stay far away from each other's territory.

Alignment: The introspective Menta cyclopeans like to gather facts before passing judgment, making most of them neutral or lawful neutral. The far more savage and brutal feral-kind cyclopeans tend more toward chaotic and evil behavior, although the isolationists among them lean toward neutral evil.

Religion: Concerned with the natural rhythm of life and the ebb and flow of fate in the universe, cyclopeans pay little heed to most religions. Those who do pray to deities commonly worship Obad-Hai (representing balance in nature), or Boccob (the uncaring deity of magic). Cyclopeans with a violent bent (which occurs most commonly among the feral-kind, but occasionally among the Menta cyclopeans) worship Nerull or Erythnul. Overall, however, cyclopeans like to make their own judgment on matters and dislike those who preach to them or make them targets of religious conversion. Regardless of their beliefs, all cyclopeans possess deep convictions pertaining to their heritage - the Menta cyclopeans believe Menta begat their species, while feral-kind see themselves as the wronged descendants of ancient cyclopes from long ago.

Language: Cyclopeans speak Giant as their natural tongue, although those who live close to other races learn to speak Common as well. Linguists note that cyclopeans speak a rather brutish version of Giant with a lyrical tone to their voices, a trait that most other beings find slightly hypnotic. Ocular imagery and numerous phrases discussing fate and the future fill the cyclopean dialect.

Names: As befitting their giant ancestry, cyclopeans have short, simple names. They eschew familial names in favor of titles, such as "the Dark Seer," "the Sullen," or "the Waywalker." Only other cyclopeans (or sometimes the tribe as a whole) grant such titles. Titles might change over time as cyclopeans experience life-changing events. A few adopt the naming conventions of other races, particularly dwarves and gnomes, accepting this additional name as just another way to make themselves out as individuals.

Male Names: Brengar, Corvor, Gorr, Merr, Tuffor, Ulbur, Warror.

Female Names: Emara, Kelara, Lessi, Nallo, Oova, Tamri, Veshe.

(From Monstrous Manual - 1993):

Cyclopskin:

A diminutive relative of true giants, cyclopskin are single-eyed giants that live alone or in small bands.

The typical cyclopskin weighs around 350 pounds, and stands 7� feet tall. A single large, red eye dominates the center of its forehead. Shaggy black or dull, deep blue hair falls in a tangled mass about its head and shoulders, its skin tone varies from ruddy brown to muddy yellow, and its voice is rough and sharp. Cyclopskin commonly dress in ragged animal hides and sandals. They smell of equal parts dirt and dung.

Combat: Cyclopskin are armed with either a club or a bardiche. Each will also carry a heavy hurling spear (1d6 damage) and a sling of great size (1d6 damage). They never wear armor or use shields, for their tough hide gives them ample protection from most attacks.

Cyclopskin do not bother with strategy or tactics in combat. If their opponents are out of reach, they use slings or hurl heavy spears. They can not throw boulders like their larger cousins. Since the single eye of the cyclopskin gives them poor depth perception, they suffer a -2 penalty to all missile attack rolls, but not to damage. If the opponents are close, the cyclopskin rush in to fight with their clubs or bardiches.

Habitat/Society: The single-eyed humanoids shy away from organized settlements. If left alone, they tend to leave armed groups alone, though they are not above attacking a much weaker force if they stumble across one. Cyclopskin have no regard for any form of life other than themselves. Captives are either enslaved or eaten. This doesn’t happen very often, since the cyclopskin tend to live in remote rocky places. They rarely wander more than 10 miles from their caves.

Being poor hunters, most cyclopskin clans keep small herds of goats or sheep. Some clans are nomadic, while others stay put in their caves. Each spring, regional clans meet to exchange goods and slaves and to select mates. On rare occasions a charismatic cyclopskin will arise and bring together several clans to form a wandering tribe. The largest known tribe numbered around 80 fighting cyclopskin. Such a band will aggressively raid outlying areas with a boldness uncommon in a single clan. All group decisions are made by the strongest and toughest cyclopskin in the group, usually through intimidation. This in turn leads to brawls and fist fights. There are no rules in such fights, and they can lead to permanent injury or death for the loser.

A cyclopskin cave is sealed with boulders and there is but one entrance. Inside, if size permits, there will be wooden pens to house both animals and slaves. The pens always have roofs of either wooden bars or the natural cave ceiling.

At night, a large boulder or stout wooden gate is placed at the entrance of the cave to protect the cyclopskin from predators. There are no interior fire pits, since cyclopskin use fire infrequently, and then only outside their lairs. Any cyclopskin treasure will be kept in a sack in the cave.

Ecology: Cyclopskin can survive on almost any animal or plant diet. They enjoy meat of all sorts and prize it above vegetable foods. While they live off the land, they do not live with it. They have absolutely no sanitary practices, and rarely even cook their meals. They take no care to preserve their environment while hunting, and are considered to be one of the easiest creatures of their size to track.

The life of a cyclopskin is hazardous, and hence they have a short life expectancy. Besides human adventurers, there are many predators, such as tigers, giants, wyverns, and trolls, that are not above attacking a small group of these giants. However, mountain dwarves actually go out of their way to hunt cyclopskin, receiving the dwarven bonus against giants.

Cyclops:

These larger versions of their slightly more common cousins are usually found in the extreme wilds or on isolated islands, where they scratch out a meager existence by shepherding their flocks of giant sheep. Cyclopes can hurl boulders up to 150 yards away, inflicting 4d10 points of damage.