Efreeti are one of the four genie races of the multiverse of Dungeons & Dragons, being associated with the Elemental force of Fire. Like all genies, they are natives of either the Elemental Planes, specifically the Plane of Fire, or the Elemental Chaos, depending on whether you look at them from the perspective of the Great Wheel or the World Axis.
Resembling fiends with their crimson skin, fiery hair, glowing eyes, fangs, claws and short horns, efreeti are obviously evil the moment you look at them, and in this case, appearances are not deceiving. Efreeti are rapacious tyrants who crave to dominate and subjugate mortals, surrounding themselves with slaves, servitors and thralls. Yet, at the same time, they are weirdly charming and alluring, excelling at manipulating and beguiling the unwary. Denizens of the Plane of Fire, efreeti are the genie race most interested in interacting with the rest of the multiverse, and as such the capital city of the efreeti - the City of Brass - is one of the more important planar metropoli, though still inferior to Sigil, of course. It is ruled over by the Sultan of the Efreet. They are the dominant race of the Plane of Fire, and thusly rule over large portions of the populations of fiery elementals, especially salamanders and azers.
The efreeti war on... pretty much everyone who seeks to stop or thwart them, but have a particular loathing for the marids (who are their enemy element) and the djinni (whose love of freedom and respect for mortals incenses the slave-taking efreeti).
Ironically, efreeti are the genies most likely to be enslaved by conjurers, sha'ir or, well, anybody who knows the proper magic. This is because efreeti are unique amongst geniekind in that they can grant true wishes practically at-will! Efreeti can grant three wishes per day to any nongenie... although they absolutely hate using this ability (in no small part because their superiors will find out and call them to account for granting wishes), and wherever possible they will try to turn wishes sour on their foes, unless the wish is being made by a true ally or somehow serves the efreet's purpose. Strangely, noble efreeti have no particularly greater power than this.
Hulking genies of the Elemental Plane of Fire, the efreet are masters of flame, immune to fire and able to create it on a whim. Fine silk caftans and damask robes drape their magma-red or coal-black skin, and they bedeck themselves in brass and gold torcs, chains, and rings, all glittering with jewels. When an efreeti flies, its lower body transforms into a column of smoke and embers.
Haughty and Cruel: The efreet are deceptive, cunning, and cruel to the point of ruthlessness. They despise being forced into servitude and are relentless in pursuit of vengeance against creatures that have wronged them. Efreet don't see themselves in this light, naturally, and regard their race as fair and orderly, even as they admit to an enlightened sense of self-interest.
Spiteful Slavers: Efreet view all other creatures as enemies or potential serfs. They raid the Material Plane and the elemental planes for slaves, which they capture and bring back to their homes on the Elemental Plane of Fire. The efreet rule as oppressive tyrants, promoting only the cruelest among their slaves. Those overseers are given whips to help keep the rank-and-file slaves in line.
Planar Raiders: Most efreet reside on the Elemental Plane of Fire, either in great domed fortresses of black glass and basalt surrounded by churning lakes of fire, or in the fabled City of Brass. Additionally, efreet military outposts thronging with their minions and slaves can be found scattered throughout the planes. On the Material Plane, efreet dwell in fiery regions such as volcanoes and the burning expanses of the world's deserts. Their love of the desert brings them into conflict with the djinn that ride the desert whirlwinds, and with the earthbound dao. Efreet utterly despise marids, with whom they have maintained a passionate conflict throughout the history of both races.
Efreeti of the World Axis are... pretty much the same as their counterparts in the Great Wheel! What can we say, it's an obvious winning formula? The "evil merchant princes" aspect of efreeti society is played up in this version, however, with more emphasis on the efreeti being planar movers and shakers - with its indigenous temperature lowered from "lethal save at the efreeti's whims" to "scorching hot summer's day", the City of Brass is also considerably more important in this cosmology, being one of the big planar trade hubs of the World Axis.
The precise origins of the efreeti? Nobody actually knows. Theories include being the archetypical "fire race" of the multiverse (thus, other fiery creatures, including fiends, are merely copying the efreeti), being yet another fiery creation of the Primordials, being descendants of rebellious devils, being the creations of a god that defected to the side of the primordials, or even being the fruit of a forbidden love betwixt god and primordial.
Alongside their hated rivals, the Djinni, efreeti are the oldest of the four genie races in D&D metalore, having debuted in the original "white box" for Dungeons & Dragons back in 1974. They were converted to Advanced Dungeons & Dragons 1e in the original Monster Manual, and to BECMI in the ExpertSet.
They first made their appearance in AD&D 2e under the "genie" heading in the Monstrous Compendium Volume One, which was then reprinted and in the Monstrous Manual. The noble efreet and the Sultan of the Efreet appeared for the Al-Qadim setting in the Monstrous Compendium Al-Qadim Appendix. The efreet also appeared in this setting under the header "Genie of Zakhara" in the Land of Fate boxed set.
In Dungeons & Dragons 4th Edition, it was the only genie race to appear in the original Monster Manual. The race's lore would be fleshed out in both the 4e Manual of the Planes and in the Elemental Chaos splatbook "Secrets of the Plane Below", such is their prominence in the World Axis.