Elves are a race associated with green mana; they are ubiquitous throughout the multiverse, second in prominence throughout the many worlds only to humans.  They typically live in forests, and are close to the land. In the game itself, many elves produce additional mana. Most elves look much like humans, only with pointed ears. Some types of elves have very distinctive physical features, however, such as blue or green skin or elongated limbs.
Most elves live far longer than humans, but it's unclear exactly how much. Eladamri was over 150 years old and considered to be in his prime. Ravnican elves not only live far longer than humans but also mature faster; it is unknown if this is common to all elves or just those of Ravnica.
Elves can be found in virtually every plane throughout the multiverse. To date, Kamigawa, Ulgrotha, Mercadia, and Theros are the only natural planes to have no known races of elves, and only small portions of some of these have been seen. According to the creative team, Elves were once present on Innistrad, but were driven to extinction.
The former subtype Rider (Elven Riders) is incorporated into the Elf class.
While the Shards of Alara were separated, elves only inhabited Naya, but after the Conflux they are free to roam the whole plane again. Their society is guided by a seer called the "Anima", which is related to their myth regarding Cylia.
During his exile, Yawgmoth turned the Creeping Mold of Argoth into a virulent plague that ate away the elves there. He also kidnapped their priestess, Elyssendril Lademmdrith, and her healers, ordering the elves to pay ransom for their leader and their cure. When the elves paid, he delivered to them only sweetened water and 12 dead healers.
Elyssendril survived, and was later part of the delegates sent to Halcyon on behalf of the Thran Alliance against Yawgmoth. During this time it was mentioned as she was of the Daelic elves, and that she represented a vast confederation of woodland nations on the Domains. Since Argoth is not part of the Domains, this is a bit of a mystery.
When, millennia later, Harbin stumbled upon Argoth, he was helped by an Argothian elf. This proved the doom of the island however, for Harbin told his father Urza of the island. Urza soon traveled to it to use it for resources in his war against his brother Mishra. The elves and other forest dwellers fought valiantly, but ultimately they were all destroyed when Urza activated the Golgothian Sylex. The following Sylex Blast completely decimated the island, leaving only a small part behind that would later become Fyndhorn.
During the Dark, the descendants of the Argothian elves, the elves of the Shattered Isles, frequently hired themselves out as mercenaries to the humans of Terisiare, for it gave them an opportunity to vent their hatred at humankind in battle.
The Fyndhorn elves were the survivors of the Argothian elves. They were slightly more open than their ancestors, engaging in diplomacy with the humans of Kjeldor via the Juniper Order. When the Ice Age ended and the sea level rose, Fyndhorn was swallowed by the sea. Kaysa and Jaeuhl Carthalion led the refugees to Yavimaya.
Yavimayan elves have very spindly, elongated limbs. One notable difference between the elves of Yavimaya and those of other parts of Dominaria is the connection between the elves and Yavimaya itself. While all elves have strong ties to the land, the elves of Yavimaya are actually part of a hive culture, sharing the thoughts of Yavimaya simultaneously with their own. During the third phase of the Phyrexian Invasion, part of Yavimaya was displaced to Urborg. It is currently unknown if any elves from the Yavimaya "colony" are still living. Lord Windgrace is now the leader of the displaced portion of Yavimaya. In addition to the spindly, telepathic elves of Yavimaya, the forest also seemed to be home to some "normal" elves as well, including some barbaric elves with a warlike culture.
Elves of the Domains
When Elyssendril Lademmdrith was sent to Halcyon on behalf of the Thran Alliance against Yawgmoth, it was mentioned that she was of the Daelic elves, and that she represented a vast confederation of woodland nations on the Domains. Since Elyssendril was a priest of Argoth, which lies on Terisiare and not in the Domains, this was likely a mistake on the author's part.
Up until the Phyrexian Invasion, the Llanowar Elves were very xenophobic, and lived in seven kingdoms, called elfhames, in the forest of Llanowar. They worshiped the planeswalker Freyalise as a goddess. Warriors among the Llanowar elves, especially the Order of the Steel Leaf elite, wear distinctive white skin-paint, tattoos, goggles, and a mohawk. 
The Savaen elves live in Savaea, a forest on an island to the southeast of Aerona. Savaen culture placed great importance on the purity of the land. They had a brief era of prominence during the Dark.
The Skyshroud elves were one of many species and races transported by Phyrexians to Rath upon the artificial plane's creation. Much like everything else on Rath, their origins are lost to time. During the Rathi Overlay, the Skyshroud forest planeshifted to Keld, where the elves took up worship of Freyalise. It is as yet unknown what happened to the elves after their goddess's death and Skyshroud's destruction in the Time Spiral crisis. Many of the elves of Skyshroud had pale gray or bluish skin with faint splotches on the sides of the face. As Dominaria's mana was sapped by time rifts, most Skyshroud elves became sickly and emaciated due to malnutrition.  
Whispering Wood Elves
The elves of Norwood inhabit the distant island-continent of Caliman on Dominaria. Norwood elves are very tall and have much longer ears than most other elves. They were in conflict with the humans of the Talas, and their warriors sometimes rode moose into battle.
The Quirion elves of Corondor were great allies of the forces of good. Their culture produced many explorers, and their magic was attuned to every color of mana. The Quirion elves organized into numerous different clans, each with their own leaders, called exarchs. Many Quirion elves, followers of the human wizard Mangara, immigrated to the southern continent of Jamuraa.
The Calthyn elves are a clan from the White Woods of Corondor, part of the Quirion Sovereign. They lived close to the River Estolade, and were enemies of the Kieryn elves, who they fought in order to decide which tribe had the right to speak with the Great Spirit. One of their leaders was Exarch Finovar
The Kieryn clan from the White Woods of Corondor, were part of the Quirion Sovereign. They lived near the River Estolade, and were enemies of the Calthyn elves, who fought over the right to speak with the Great Spirit. The Kieryn used wing-capes to fly through the forest. They were led by Exarch Amadis, and met with Kristina of the Woods and Jared Carthalion.
As noted above, many Quirion elves migrated from Corondor to Jamuraa's northwestern subcontinent. In addition, a race of elves, some with dark brown skin, dwelt in Jamuraa's southern regions, near the Empire of Madara.
The elves of Sarpadia dwelt in the forest of Havenwood. When food supplies ran low because of the coming Ice Age, the Havenwood elves infused their fungus with magic in order to increase their growth, inadvertently creating the monstrous thallids, who overran the elves and caused their extinction. Havenwood elves looked much like elves elsewhere. Some of their warriors wore distinctive blue body-paint.
The Garan elves lived on the highlands at the edges of the Tamingazin Valley. They could easily be mistaken for humans, as they were very similar in appearance — lacking even pointed ears. It was said that this ancient race possibly had a common ancestor with humankind. The main characteristic setting the Garan elves apart from humans was their great natural beauty and their wide eyes whose irises changed color according to their mood. Garan elves were also very deadly warriors, fighting solely with their own bodies and relying on their own speed, agility, and martial arts. Weapons were forbidden in their culture, and an elf who used them would be executed. They could be very brutal toward their own children, attacking them occasionally with fatal blows to teach them self-defense, killing those who were unable to defend themselves, ensuring that only the strongest children survive. They believe that in afterlife they will find themselves in a place they call Tarak Ah. The history of the Garan elves before their arrival in the Valley is unknown. Some tales say that the Garan elves once used weapons, very long and flexible swords which could be used almost like lashes. None could stand against them, but one day conflict arose between them, and civil war almost engulfed their race. The survivors swore never to use a weapon again and to kill those who dared. The Garan have a strict hierarchy, the full name of every member is comprised of his or her first name followed by the rank.
Many people from the northern hemisphere fled to Otaria after the Phyrexian Invasion of Dominaria. The elves among these mainly came to live in the Wirewood Forest. The elves lived in a state of symbiosis with the native beasts and insects of the forest.When the Mirari started spreading its mana waves over the continent, many of the elves mutated; most became spindly creatures with plant-like features, while some became hulking brutes with barklike skin. It's unknown if all Wirewood elves were mutated, or if the mutations bred true.
The elves of Lorwyn are the dominant race of the plane. Unlike other elves, they are a brutal race of supremacists who hide their savagery behind a facade of beauty and sophistication. They are obsessed with physical attractiveness and believe that those who do not meet their standards of perfection (including all races other than themselves) deserve nothing but extermination. The elves divide themselves into numerous tribes and castes, the most powerful of which is the Gilt Leaf. Lorwyn elves are tall and thin. They have ram-like horns (males' horns being longer than females') and cloven hooves on their feet. Unlike any other known race of elves, those of Lorwyn have relatively short life spans of about 30 to 40 years.
In Lorwyn's counterpart, Shadowmoor, the elves are the only race that embrace a quest of preserving what they consider beauty. Physically they remain mostly the same except their horns which are covered with thorns.
The elves of Mirrodin were not native to that plane, but were instead drawn there from some other world by Mirrodin's mad guardian, Memnarch. The Viridian elves resided in the vast copper forest known as the Tangle. They were staunch enemies of the myr and other artifact creatures. The elves held the Radix as a holy place, and looked to the trolls of Tel-Jilad for spiritual guidance. They were in conflict with the vedalken of Lumengrid and their drones. Viridian elves were marked by their bright green or pale white skin, while the mycosynth growing within the plane caused them to grow intricate plates and spikes of copper across their bodies.
With the coming of New Phyrexia, many elves have been compleated by the glistening oil and become a part of the Phyrexian faction, the Vicious Swarm. Still residing in the Tangle they act as wardens, led by the de factor leader of the region Glissa. Now they accelerate the growth of the Phyrexian monstrosities which roam the forest or hunt down the last of their kin who still hide in the forest.
Devkarin are the dark elves of Ravnica.  They make up one of the two elite classes of the Golgari, the other elites being the teratogens. They are presided over by their matka, a high priestess, who until recently was Savra.
The Silhana are the Ravnican elves that are part of the Selesnya Conclave. The Silhana are master archers who stalk the rooftops of the city-plane. Some Silhana, the Elves of Deep Shadow, were cast out of the Conclave long ago and joined the Golgari.
There was once a third tribe of elves on Ravnica, one that became largely extinct during the pre-Guildpact wars; the survivors joined the Simic Combine. Little is known about them, but both the Devkarin and the Silhana believe they were very cruel and unpleasant. Simic elves seem to have been mostly bald. As time went by, almost all of the Simic elves subjected themselves to strange biological experiments, adding biomechanical implants or splicing their genes with those of other creatures, such as snakes.
The elves of Zendikar are a highly adaptive race that make their homes in the treetops of Murasa and Bala Ged. Natural risk takers, the elves have a strong survival instinct and fearless demeanor making them well suited for life on this dangerous plane. They lack a formal religion, instead practicing forms of mysticism as well as communing with spirits of their ancestors.
The Joraga Nation is seated in the Tangled Vale portion of Bala Ged. Their leader is Speaker Nen, although the various tribes are only loosely connected. Each tribe follows the migratory pattern of a particular species of beast, adapting the creature into their magic and combat styles. Nomadic by nature, the Joraga eschew outsiders and hold even the other elves of Zendikar in disdain.
The Kazandu Splinter
The Kazandu Splinter is a small faction of elves located in Kazandu region of Murasa. Former Tajuru, they broke off from the nation refusing to see Speaker Sutina as their leader. Their life on the dangerous cliffsides and in the jaddi-trees has fundamentally changed their outlook from their former brethren.
Mul Daya Nation
Mul Daya is a secretive nation located in the Guum Wilds of Bala Ged. They can be easily recognized by their face-painting and tattooing. While their living leader is Hazzan, he himself follows the edicts of a centuries old elvish spirit named Obuun. Through their leadership, the Mul Dayans have become adept spies and assassins with the elite calling themselves "vine ghosts." Mul Dayan Soulspeakers openly practice a blend of mysticism and necromancy to better commune with their ancestors.
Through the leadership of Speaker Sutina the Tajuru nation has become the largest and most prominent elf faction on Zendikar. Based in the massive treetops of Murasa, the Tajuru are open to other races and highly skilled innovators. Their capital is the Tumbled Palace based on the cliffs of Sunder Bay; Sutina has often been seen overlooking the water just before Lorthos, the Tidemaker appears (although any connection between the two is unknown).
The result of mating between elves and humans (or, more rarely, elves and other races), half-elves have shorter lifespans and less delicate features.
Gaea's Skyfolk were an indirect product of the Phyrexian Invasion of Dominaria. As the whole world mobilized its reserves, even ancient adversaries cooperated together, lending their diverse skills into the service of the common good. The Skyfolk were partially of merfolk and partially of elvish origin, combining the unique features and skills of both races into one. The detailed description of their abilities is not available, but the major one was the ability to fly. The details of creation of these prodigal creatures are, however, not known.
- Arathel — Queen of Norwood
- Fonn Zunich — Half-Silhana elf/half-human
- Kaysa — Half-Fyndhorn elf/half-human
- Marhault Elsdragon — Half-Jamuraan elf/half-human
- Myczil Savod Zunich — Half-Devkarin elf/quarter-Silhana elf/quarter-human
- Merieke Ri Berit (possibly; lineage unknown)
- Radha — Half-Skyshroud elf/half-Keldon human
Tribal - Elf
1/1 green Elf Warrior Creature tokens are produced by:
- Ambassador Oak
- Elvish Promenade
- Flourishing Defenses
- Gilt-Leaf Ambush
- Hunting Triad
- Imperious Perfect
- Lys Alana Huntmaster
- Nath of the Gilt-Leaf
- Presence of Gond
- Prowess of the Fair
1/1 green Elf Druid Creature tokens called "Llanowar Elves" are produced by:
1/1 green and white Elf Warrior Creature tokens are produced by:
- Eladamri, Lord of Leaves - first Lord to grant shroud, forestwalk, also because of its wording it is the first lord to grant something to all other Elf permanents, including non-creatures like Prowess of the Fair.
- Elvish Archdruid
- Elvish Champion
- Ezuri, Renegade Leader
- Imperious Perfect
- Joraga Warcaller - first Lord to grant something based on the number of +1/+1 counters on it
- Joraga Treespeaker - when Level 5+
An Argothian elf. Art by Daren Bader.
Fyndhorn elves. Art by Justin Hampton.
A Yavimayan elf. Art by Greg & Tim Hildebrant.
A Yavimaya barbarian. Art by Don Hazeltine.
A Llanowar elf. Art by Kev Walker.
A Savaen elf. Art by Ron Spencer.
A Skyshroud elf. Art by Mark Tedin.
A Havenwood elf. Art by Mark Poole.
A Lorwyn elf. Art by Quinton Hoover.
A Viridian elf. Art by Scott M. Fischer.
A Devkarin elf. Art by Zoltan Boros & Gabor Szikszai.
Silhana elves. Art by Edward P. Beard, Jr.
One of Gaea's skyfolk. Art by Terese Nielsen.
- Mark Rosewater. (August 18, 2008.) "To Thine Own Elf Be True", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. ( July 14, 2004.) "The Elves of Argoth", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. (August 16, 2005.) "The elves of Llanowar", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. (October 02, 2006.) "Time Spiral Style Guide: Green", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. (October 19, 2006.) "Sketches: Search for Tomorrow", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. (October 27, 2005.) "Ravnica Style Guide: Golgari", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Creative Team. (Wednesday, September 30, 2009.) "A Planeswalker’s Guide to Zendikar: Bala Ged and Elves", Daily MTG, magicthegathering.com, Wizards of the Coast.