Sources and influences on the development of Dungeons & Dragons

Many elements in the game Dungeons & Dragons were inspired or drawn from other sources. In many cases, people are unaware that specific elements have origins outside the game.

Barbarian
The barbarian appeared as a class in AD&D's Unearthed Arcana. The class was heavily inspired by Howard's Conan, whose adventures were a major source of inspiration for the game. As Conan was often deeply suspicious of magic, this barbarian was limited in its ability to use magical items until higher levels. This class was a great leaper and an able climber, like Conan. The D&D 3.5 version retains some similarities, but eliminated the disdain for magic. A less psychotic version of a berserker's fury was incorporated as the rage ability (previously, berserkers had been NPCs or monsters) for barbarians. The new barbarian remains close to its archetypal founder, however, possessing a trap sense and uncanny dodge abilities similar to Conan's keen eye for trouble.

Bard
The bard, appearing originally in AD&D, was inspired by stories of the Celtic bard, a musician and keeper of ritual lore, related to the druidic tradition. The original bard was a dual-classed fighter/thief/druid. Later editions diverged from this inspiration, making the bard a sort of scoundrel, minstrel, and enchanter with a knowledge of legends.

Cleric
The cleric is largely inspired by folklore of the medieval cleric of Templar. Like the Templars described in White's The Once and Future King, clerics in D&D were forbidden edged weapons by religious vows. Their spellcasting abilities paralle the miracles of saints, but bear little resemblance to the folklore of the fighting priest. AD&D 2nd edition introduced the concept of specialty priests, of which the druid is an example, who had different spell capabilities and different weapon choices. Clerics, in 3.5, are drawn to maces and staves primarily by a lack of proficiency with martial weapons, and to a lesser degree by a deity's favored weapon. The warhammer, typically presented as a small sledge, rather than the historical pick-like weapon, is another iconic cleric weapon, wielded by dwarven clerics in 3.5, with more than passing resemblances to the hammer of Thor.

Druid
Although inspired by lore of Celtic priests in pre-Roman times, druids in Dungeons & Dragons bear little resemblance to their historical counterparts. A druid, in D&D, is a divine caster who reveres nature. They possess special supernatural powers, and do not wear metal armor.

Monk
The monk is based on the Asian martial arts tradition, particularly wuxia and appearances of kung fu, karate, and ninjitsu in the later part of the 20th century in the US. Many of their abilities are those ascribed to sifus and Zen masters.

Paladin
The paladin, named for Charlemagne's pious champions, is inspired by legends of chivalry and piety, particularly those of the European Renaissance. Primarily inspirations seem to be Galahad from the Arthurian saga, the same Templars that inspired the cleric class, and warrior-saints such as Joan of Arc and the fables of Saint George.

Ranger
Largely inspired by the character of Aragorn in The Lord of the Rings.

Rogue
Although the plucky rogue, thief or trickster character is a staple of human legends, the D&D rogue and his ancestors a special debt to Bilbo Baggins, the hobbit burglar, and The Grey Mouser, Fritz Leiber's swashbuckling rogue. Especially, the "thieves guilds" of Dungeons and Dragons seem to have been inspired by the organized crime of Leiber's Lankhmar.

Wizard
Wizards memorize their spells in the fashion of magicians from Jack Vance's Dying Earth series of novels.

Dwarves
Dwarves come from The Lord of the Rings, although modified in translation. Tolkien's dwarves were already less sorcerous and fey than their legendary Anglo-Saxon forebears. D&D dwarves derive their greed, stubbornness, and martial character essentially from the company of dwarves who hire Bilbo in The Hobbit to serve as an "expert treasure hunter."

Elves
Elves in Dungeons & Dragons derive mainly from the works of Tolkien, with their long lives, affinity for wild places, ancient magic, grace, benevolence, dreamless sleep, and humanoid appearance. However, they also seem to draw inspiration from the sorcerous elves of Poul Anderson, although their are less capricious and sociopathic. They also serve as an ancient civilized race, similar to the Melniboneans or Vadhagh of Michael Moorcock.

Halflings
Halflings are hobbits, after a lawsuit-inspired name change (halflings is also a word Tolkien used for hobbits, but seemingly less contentious to the Tolkien estate). Recent versions have incorporated some elements of the Dragonlance series' kender, as well as colorful stereotypes of gypsies.

Chimera
The chimera comes from Greek myth. The original could spit or glance with lightning or poison. The D&D version, having a dragon head, could breath fire. The third edition version could have the head of any chromatic dragon; a blue dragon chimera would spit lightning, like a classic chimera.

Djinn
The djinn comes from Arabic folklore. In D&D it is a type of genie.

Dryad
A dryad is a demigod in Greek myth, a type of goddess or nymph associated with nature.

Efreet
The efreet, a type of genie in D&D, comes from Arabic folklore. They live in a City of Brass.

Goblin
goblins appear in Tolkien's The Hobbit, whereas the same creatures are usually referred to as orcs in The Lord of the Rings.

Golem
The word golem comes from Jewish folklore, and refers to a man of clay, named Joseph, created by a community as a protector.

Nymph
Nymphs come from Greek myth, in which they exhibit their blinding beauty.

Orc
Orcs come from Tolkien's The Lord of the Rings where they are described as bestial, brutal, and evil humanoids. The term orc, before Tolkien, meant a monster, possibly an ogre, but usually referred to a type of sea monster.

Simurgh
The simurgh is a creature of Persian myth.

Treant
Treants are tree-like creatures. They were called Ents in earlier versions, before a lawsuit from the Tolkien estate that prompted many other changes.

Troll
Trolls come from Northern European folklore. The D&D version was inspired by a regenerating troll that appear in Poul Anderson's Three Hearts and Three Lions.

Wyvern
The wyvern appears as a heraldic figure.

Ioun Stones
Ioun stones come from the Dying Earth tales of Jack Vance, with little alteration.

Three Bladed Sword
This oddity from Unearthed Arcana seems to have come from the film The Sword and the Sorcerer.

Mithral
A lightweight, shiny metal inspired by Tolkien's mithril.

Prismatic Spray
The prismatic spray comes from Vance's "Mazarian the Magician", which features the Excellent Prismatic Spray.