Like all great intergalactic sagas, the Marvel movies explore a vast galaxy full of different planets and alien species. Although the Guardians of the Galaxy, which established a galaxy beyond the Nine Realms and gave producers infinite possibilities when it came to incorporating alien characters.
In the MCU timeline, aliens first arrived on 21st century Earth when Thor, an Asgardian, crash-landed in New Mexico, alerting authorities to the existence of extraterrestrial life. Thor's cooperation with the Avengers quickly expanded humanity's vision of the universe as he taught them about the different worlds and governments. Earth's wider population first became aware of alien life when Avengers: Infinity War.
One important fact to note is that among the multitude of alien races in the universe, there are several political and military organizations. Although many of the MCU's notable alien characters are of these organizations, their races, and home planets are never explicitly identified. Ebony Maw, of the Black Order, for example, is a powerful telekinetic who battles the Avengers, but his species is never named in the Cinematic Universe. With Phase Four set to explore even more of the universe, here is a catalog of every alien species seen in the MCU so far.
The Nine Realms
In Marvel lore, the Nine Realms make up a huge part of intergalactic civilization. With a multiverse full of superheroes and aliens, the eight planets orbiting Midgard (a.k.a. Earth) are the most relevant to humanity's continued existence. All nine realms are connected by the Bifrost, a rainbow bridge that allows instant travel between worlds. Each world, inhabited by different species, has its own conflicts and alliances with others, creating a complex web of intergalactic politics.
Asgardians
Chief among the Nine Realms is Asgard, home to Thor and Odin. Although Norse mythology on Earth was influenced by the early presence of Asgardians in Scandinavia, the well-known "gods" are actually Thor: Ragnarok.
There are a couple of known subspecies native to Asgard. During The Avengers, Thor mentions a race of creatures called the Bilgesnipe, which he describes as, "huge, scaly, big antlers." According to Thor, they're "repulsive," trampling everything in their path. Also native to Asgard are the steeds of the Valkyries, which resemble horses with wings. One such pegasus appears in Avengers: Infinity War. A similarly powerful mount, the Asgardian wolf Fenris who was resurrected by Hela, appears in Thor: Ragnarok.
Vanir
Allies of the Asgardians include the Vanir, native to Vanaheim, of whom Hogun is a member. Like Asgardians, Hogun is long-lived and much stronger than an average human. He first appeared in the Warriors Three, a group of brothers-in-arms that also includes Asgardians Fandral and Volstagg.
Dwarves of Nidavellir
Dwarves, also allies of Asgard, didn't appear onscreen in the Marvel Cinematic Universe until Avengers: Infinity War. During the film, Thor sought help in creating a weapon capable of defeating Thanos. In traveling to the home planet of the dwarves, Thor found Eitri (Peter Dinklage), the King of Nidavellir and last survivor of his race. Like all dwarves, Eitri is a skilled forger and blacksmith. His planet is home to a forge powered by the heart of a dying star, the only one in the galaxy capable of creating weapons made from the metal Uru. Eitri and his people are responsible for creating Thor's hammer, Mjolnir, and the Infinity Gauntlet, capable of harnessing the power of the Infinity Stones. With Thor's assistance, Eitri also created Stormbreaker, an axe destined to be the greatest weapon in Asgard's history.
Light & Dark Elves
The world next nearest to Asgard is Alfheim, home to the Light Elves, who have not yet made an appearance in the Marvel Cinematic Universe. In the comics, the light elves are a generally peaceful race, although, like Asgardians, they have superhuman strength, speed, and agility. Per the lore, they have a talent for archery and weakness to iron.
Opposite the Light Elves are a race of beings who are have been fighting Asgardians for millennia. Thor: The Dark World. About 5,000 years before the events of The Avengers, the Dark Elves, led by Malekith, fought the Asgardians in an effort to bring eternal darkness to the universe. The Dark Elves later reawakened to continue that mission, attempting to use the Aether (later used to make the Reality Stone) to remake the Nine Realms. Thor and Loki ultimately defeated the elves and they were all but wiped out.
Like many of the races of the Nine Realms, the Dark Elves are more advanced than humans when it comes to strength and speed. In Thor: The Dark World, the Dark Elves are a match for the Asgardians, mounting a successful attack against their home world. The Dark Elves also have a quasi-subspecies of elite warriors called the Kursed, who become almost invulnerable with the use of mystical Kurse Stones, but are doomed to be eventually consumed by darkness. Algrim the Strong, who died in battle against Loki and Thor, was one of the Kursed, and is shown knocking aside Thor's hammer before being sucked into a black hole.
Frost Giants
Another formidable enemy of Asgard is the Frost Giants, who originate from Jotunheim. Frost Giants are generally much larger and taller than humans and can manipulate and control ice, using it to form weapons and armor. of the species have blue skin and bright red eyes, along with facial ridges and other unique bone structures. The most notable Frost Giant in the MCU is undoubtedly Loki, whose true heritage as the biological son of Laufey (King of Jotunheim) was revealed in Thor. During the film, Asgardians also face off against Frost Beasts, another species native to Jotunheim.
Fire Demons
The final two realms in the system, Niflheim and Muspelheim, are each seen in Thor: Ragnarok. The latter is home to the fire demons and their leader Surtur, who was destined to destroy Asgard. Thor is seen visiting Muspelheim in Thor: Ragnarok, where he battles Surtur, an army of fire demons and a fire dragon, eventually escaping via the Bifrost. As one might expect, Surtur and his cohort have power over fire, using it to attack enemies. Although Thor defeats Surtur in the first few minutes of Thor: Ragnarok, he later frees him in an effort to destroy Hela. The two appear to take each other out, destroying Asgard in the process.
Niflheim, meanwhile, is the world to which Thor's sister, Hela, was banished after being defeated by Odin. Not much of the world is seen in the MCU, but it is described in the comics as a dark, cold, and misty planet, including a region known as Hel. Niflheim doesn't have any native species, instead acting as a kind of isolated prison and afterlife for the people of the universe.
Titans
The most powerful enemy the Avengers have ever faced, Thanos, is a Titan, originating from a planet of the same name. The most notable trait of the Titans is their overwhelming strength. The physical ability of Thanos is unmatched by any of the Avengers, including Thor and the Hulk. Thanos' size and strength allow him to wield the Infinity Stones and defeat the team's heavy hitters, including Vision. Thanos is also one of the only beings known to be able to damage vibranium, shown when he broke Captain America's shield in Avengers: Endgame. During the final battle, Thanos is also seen outmaneuvering some of the faster of the team, including Iron Man, hinting at superhuman speed and agility.
Alien Species In Thor
Several alien species born outside the Nine Realms are seen throughout the Thor franchise, particularly in Thor: Ragnarok. When Thor is marooned on Sakaar, he encounters a friendly Kronan named Korg, from the species of giant humanoids made of rocks. Korg appears in several other movies in the MCU, always by Thor's side. A Kronan warrior also appeared in Thor: The Dark World, fighting against Asgardians.
Sakaarans, a race of insectoids native to Sakaar, are also present throughout Thor: Ragnarok. Miek, a small, purple friend of Korg's, is a Sakaaran who was forced to compete for the Grandmaster. Sakaarans often work as soldiers-for-hire, and have served Thanos and other enemies of the Avengers as mercenaries. Sakaar is also home to a multitude of other aliens who became stranded on the planet, although their species and home planets are never identified.
