The concept of the Nine Realms was introduced alongside Thor himself in Marvel Comics, first appearing in Journey into Mystery #83 in August 1962. Created by writer-editor Stan Lee, scripter Larry Lieber, and penciller-plotter Jack Kirby, the realms were a direct adaptation of the nine worlds of Norse mythology. This mythological foundation provided a rich, pre-packaged universe for Kirby's cosmic imagination and Lee's dramatic storytelling. Kirby's art defined the initial visual language of the realms, particularly Asgard, with its gleaming spires and the iconic Bifrost Bridge. The other realms were fleshed out over decades, with creators like Walt Simonson, during his legendary run on The Mighty Thor in the 1980s, providing definitive depictions of realms like Muspelheim and its ruler, Surtur. This ongoing world-building transformed the Nine Realms from a simple fantasy backdrop into a complex and integral part of the Marvel Universe's cosmic tapestry.
The in-universe history of the Nine Realms is a saga of creation, conflict, and cosmic cycles, with significant differences between the comic and cinematic universes.
In the prime comic continuity, the Nine Realms are not planets in the conventional sense but are separate dimensions, each a distinct universe with its own physical laws, often appearing as flat, planetoid-like bodies floating in their own dimensional space. They are all connected and held in cosmological balance by the mystical energy of the World Tree, Yggdrasil. The origins of this structure are tied to the primordial entity known as the First Cosmos and the subsequent cycles of universal death and rebirth. The current iteration of the realms was shaped by the actions of Odin and his brothers, Vili and Ve. At the dawn of time, they battled the fire demon Surtur, who sought to burn the branches of Yggdrasil and bring an end to all things. After imprisoning Surtur in Muspelheim, Odin established Asgard as the nexus and guardian of the Nine Realms, forging a tenuous peace through conquest and diplomacy. A critical aspect of the comic universe's Nine Realms is the concept of Ragnarok. This is not a single event but a recurring cycle of death and rebirth that the Asgardians are fated to endure. Odin has spent millennia attempting to break this cycle, which has seen Asgard and its inhabitants destroyed and reborn countless times, often with slight variations. This cyclical nature is a fundamental truth of their existence, a stark contrast to the more linear timeline of the MCU.
The MCU presents a more scientifically grounded, though still fantastical, version of the Nine Realms. As explained by Thor to Jane Foster in Thor (2011), the realms are nine distinct worlds located in a relatively close, gravitationally-linked cluster in space. They are not dimensions but actual planets. Yggdrasil is not a literal tree but a cosmic constellation or a map of the wormhole-like pathways that connect these worlds. The primary means of travel between them is the Bifrost Bridge, an advanced piece of Asgardian technology that generates a powerful Einstein-Rosen bridge. Another natural phenomenon, the Convergence, occurs every 5,000 years when the nine worlds move into perfect alignment, causing the fabric of reality to weaken and creating temporary, unstable portals between them. This event was the central plot point of Thor: The Dark World (2013). Odin's history in the MCU is presented not as a shaper of dimensions but as a conqueror who brought an end to an age of chaos. He and his firstborn, Hela, waged a bloody war across the realms to establish Asgardian dominance. After Hela's ambition grew too dark, Odin banished her and rewrote history, casting himself as a benevolent protector. His unification of the Nine Realms was an act of galactic empire-building, designed to enforce peace, a peace that began to crumble upon his death. Unlike the comics, the MCU's Ragnarok was presented as a singular, prophesied event that resulted in the complete destruction of the planet Asgard, not a recurring cycle.
The Nine Realms are the heart of the Asgardian world. While the list of nine has been generally consistent, the addition of a tenth realm in the comics has expanded the cosmology.
The pinnacle of the Nine Realms, home to the Asgardians (the Aesir). It is the realm of gods, honor, and eternal battle.
Asgard is a flat, asteroid-like landmass floating in its own dimension. It is not a sphere and does not rotate; a day-night cycle is mystically maintained. It is divided into several cantons, including the main continent where the city of Asgard—with its golden halls like Valhalla and Odin's throne room—resides. It is connected to Midgard by the rainbow-colored Bifrost Bridge. After being destroyed during Ragnarok, it was resurrected by Thor and floated for a time over Broxton, Oklahoma, before being destroyed again during the Siege event. The Asgardians now reside in Asgardia, a new city built from the remnants.
In the MCU, Asgard was a large, habitable world, visually similar to the comics' floating landmass but treated as a planetoid. It was the center of a vast and technologically advanced civilization that presented its science as magic to less developed worlds like Earth. Key locations included Odin's Throne Room, the Vault containing powerful artifacts like the Casket of Ancient Winters and the Tesseract (in the past), and Heimdall's Observatory, which housed the Bifrost. The planet itself was completely destroyed by Surtur at the climax of Thor: Ragnarok (2017) to defeat Hela. The surviving Asgardians relocated to Earth, establishing New Asgard in Tønsberg, Norway.
Our world. The human realm.
Midgard is Earth, specifically designated Earth-616. It is considered one of the most important and fiercely protected realms by Asgard due to Odin's ancient love for its fledgling human race and Thor's deep affection for its people. Asgardian influence is woven throughout its history, with many ancient myths being direct, if distorted, accounts of Asgardian activities.
Similarly, Midgard is Earth, designated Earth-199999. It holds a place of special importance to the Asgardians. The Battle of New York in The Avengers (2012), orchestrated by Loki with the Chitauri, was a direct assault on Midgard that solidified its importance in cosmic affairs. Following the destruction of Asgard, Earth became the official new home for the Asgardian people, further cementing the bond between the two realms.
The desolate, frozen world of the Frost Giants.
Jotunheim is a land of eternal ice and snow, characterized by jagged mountains and frozen plains. It is a harsh, brutal environment that has shaped its inhabitants, the Frost Giants, into a warlike and resilient race. Their king, Laufey, was a perennial foe of Odin. The realm is a place of immense elemental power, and the source of the Casket of Ancient Winters.
Depicted in Thor (2011), Jotunheim is a dying, ice-covered planet in a state of perpetual twilight. Its civilization is in ruins following a devastating war with Asgard a millennium ago, which ended with Odin seizing the Casket of Ancient Winters, the Frost Giants' primary power source. It is the birthplace of Loki, who was abandoned by his father, King Laufey, and adopted by Odin.
The Realm of the Dark Elves.
Svartalfheim is a gloomy, subterranean world of sprawling caverns, forests of giant fungi, and forges lit by strange energies. It is the home of the Dark Elves, masters of stealth, sorcery, and shapeshifting. Their leader is Malekith the Accursed, one of Thor's most persistent and cruel adversaries. The Dwarves of Nidavellir originally shared this dimension before it was split.
As seen in Thor: The Dark World, Svartalfheim is a desolate, dark wasteland of jagged black rock and dust. It was ravaged in a war with Asgard thousands of years ago when the Dark Elves, led by Malekith, attempted to use the Aether (the Reality Stone) to unmake the universe. The Asgardian victory left the realm a ruin and the Dark Elves a nearly extinct race, forced into suspended animation for millennia.
The Realm of the Dwarves, master craftsmen of the cosmos.
Nidavellir is a distinct realm, a world of deep mines and incredible forges, where the Dwarves craft legendary weapons and artifacts. They are renowned throughout the cosmos for their skill, having forged Odin's spear Gungnir and, most famously, Thor's hammer Mjolnir from the mystical metal Uru. Their king is Eitri.
In the MCU, Nidavellir is not a planet but a neutron star, harnessed and encircled by a massive, forge-like Dyson sphere structure. This incredible stellar forge is where the Dwarves, led by Eitri, created Mjolnir. As revealed in Avengers: Infinity War (2018), Thanos forced the Dwarves to forge the Infinity Gauntlet and then slaughtered all but Eitri, destroying the forge mechanism and encasing the Dwarf's hands in metal. Thor, Rocket, and Groot later traveled there to relight the dying star and forge Thor's new weapon, Stormbreaker.
The Realm of the Light Elves.
Alfheim is a dimension of breathtaking, pristine beauty, filled with lush forests, shimmering rivers, and perpetual sunlight. It is the home of the Light Elves, a noble, beautiful, and magically-gifted race who are typically allies of the Asgardians. While generally peaceful, they are formidable warriors when roused to battle.
Alfheim is mentioned by Thor and seen briefly during the Convergence in Thor: The Dark World, appearing as a vibrant, bright world. Light Elves are seen fighting alongside the Asgardians during the prologue of the same film. Beyond these brief glimpses, it remains largely unexplored in the MCU.
The Realm of the Vanir, sister gods to the Asgardians.
Vanaheim is the home of the Vanir, a sister race of deities to the Aesir of Asgard. In ancient times, the Aesir and Vanir were at war, a conflict that ended with a truce and an exchange of hostages, which led to figures like Freyja and Freyr joining the Asgardians. Vanaheim is a verdant, wild world, and its people are considered masters of a different, more naturalistic form of magic than that of the Asir.
Vanaheim is depicted in Thor: The Dark World as a forested world with medieval-style settlements. It was the site of a major battle where Thor, Sif, and the Warriors Three helped quell an invasion by marauders, one of the final conflicts in the campaign to restore peace to the Nine Realms after the Bifrost's destruction. Hogun the Grim of the Warriors Three was a native of Vanaheim.
The Realm of Fire, home to the Fire Demons.
Muspelheim is a fiery, volcanic hellscape, a dimension of eternal flame, rivers of lava, and soot-blackened skies. It is populated by Fire Demons and ruled by the colossal, apocalyptically powerful being known as Surtur. Surtur's destiny is to forge the Twilight Sword and bring about Ragnarok by burning all of existence, beginning with Asgard. The “Surtur Saga” from Walt Simonson's run is a defining storyline for this realm.
Introduced in Thor: Ragnarok, Muspelheim is a volcanic realm filled with fire demons and dragons. Surtur rules from a throne in a vast cavern. The prophecy of Ragnarok in the MCU stated that Surtur could only destroy Asgard if his crown was reunited with the Eternal Flame in Odin's Vault. Thor initially defeats Surtur, but later deliberately resurrects him to fulfill the prophecy as the only way to defeat Hela.
The Realms of the Dead.
In the comics, these are often distinct but related realms. Niflheim is a primordial realm of mist, cold, and darkness, the land of the dishonorable dead. Within Niflheim lies the sub-realm of Hel, ruled by Hela, the goddess of death (and in this continuity, Loki's daughter). Hel is specifically the destination for the souls of Asgardians who do not die gloriously in battle. Those who do are taken by the Valkyries to Valhalla, a separate paradisiacal region within the dimension of Asgard itself.
The MCU largely conflates these concepts. Hel is mentioned as a realm Hela was banished to, but its nature is unclear. After her escape, the realm itself is not shown. Hela is established as Odin's firstborn daughter, not Loki's. Valhalla is confirmed to exist as an afterlife for worthy Asgardian warriors, as Jane Foster is shown arriving there in the post-credits scene of Thor: Love and Thunder (2022). Niflheim is not explicitly named or depicted.
Yggdrasil is the lynchpin of the entire cosmology, but its nature varies greatly.
The primary method of travel between worlds.
The prophesied end of Asgard.
Considered by many to be the greatest Thor story ever told, Walt Simonson's epic saw Malekith steal the Casket of Ancient Winters, unleashing chaos. The main threat, however, was Surtur, who forged the giant Twilight Sword and led the armies of Muspelheim in a direct assault on all Nine Realms, with the final battle taking place on Earth. The saga culminated in a titanic struggle where Odin, Thor, and Loki fought side-by-side to defeat Surtur, with Odin seemingly sacrificing himself to imprison the demon.
After the last Ragnarok cycle, Thor re-established Asgard in the skies above Broxton, Oklahoma. This made the realm a target for the then-director of H.A.M.M.E.R., Norman Osborn. Osborn, using manipulated intelligence from Loki, launched a full-scale military invasion of Asgard, laying siege to the city with his Dark Avengers and H.A.M.M.E.R. forces. The event brought Earth's heroes, including Captain America and Iron Man, to defend Asgard, and resulted in the city's complete destruction and the dissolution of Osborn's regime.
This MCU-specific event is a cosmic alignment of the Nine Realms that happens every five thousand years. During the Convergence, the boundaries between the worlds weaken, creating random, temporary portals linking them. Jane Foster stumbled into one such portal, leading her to the hiding place of the Aether. Malekith sought to use the energy of the Convergence to amplify the Aether's power, allowing him to plunge all Nine Realms into eternal darkness from a nexus point in Greenwich, England.
During the 2014 storyline Original Sin, a major retcon revealed the existence of a secret tenth realm: Heven, populated by a race of winged warriors known as Angels. It was revealed that during a war in the distant past, Odin and the Angels' queen had a daughter, Aldrif. When the queen was seemingly killed, Odin, in his grief, used his power to tear Heven from Yggdrasil and seal it away, erasing all memory of it from existence. Aldrif was thought lost but was secretly raised by the Angels as Angela, a fearsome warrior who would eventually learn her true Asgardian heritage.
In the Ultimate Marvel Universe, the Asgardians were presented in a much more ambiguous light. For much of the continuity, it was unclear whether they were true gods or simply super-soldiers created by the European Defence Initiative using advanced technology and genetic engineering. Loki, in this universe, was Thor's evil half-brother who could warp reality. The “gods” were nearly all wiped out during the Ultimatum event when Loki led an army that destroyed Asgard, killing most of its inhabitants, including Thor.
This critically acclaimed animated series offered a faithful adaptation of the comic book Nine Realms. It featured a multi-episode arc where each of the Avengers was separated and transported to a different realm, forcing them to survive in hostile environments like Jotunheim and Svartalfheim while fighting to reunite. The series prominently featured classic concepts like the war with Surtur, Malekith's treachery, and the political tensions between Asgard and the other worlds.