Heimdall

"Be warned, I will honor my sworn oath to protect this realm as its gatekeeper. If your return threatens the safety of Asgard, Bifrost will remain closed and you will be left to die on the cold waste of Jotunheim."

- Heimdall

Heimdall is the all-seeing and all-hearing Asgardian and guard of the Bifrost Bridge. He can see and hear nearly everything that happens in the Nine Realms. He is the current guardian of the Asgard and protector of the Tesseract. Despite vowing to obey the orders of Odin, Heimdall is prepared to commit treason if it means protecting the Realms, as he allowed the Warriors Three to return Thor from Midgard to defeat Loki. When Asgard was attacked by the Dark Elves, Heimdall discovered his powers were blocked by the Elves so he was forced to once again commit treason to help Thor destroy Malekith and protect the Nine Realms.

Protector of the Realms
"You have great power, Heimdall. Did Odin ever fear you?" "No." "And why is that?" "Because he is my King. And I’m sworn to obey him."

- Loki and Heimdall

Heimdall is an Asgardian blessed with sensory capabilities far beyond those of other Asgardians, letting him see nearly all things that happen in the Nine Realms. His near omniscience have been put to use placing Heimdall in the role of gatekeeper to Asgard at his observatory on the Bifrost Bridge. Throughout his time as it's guardian, Heimdall ensured that no enemies were able to get past his watch and enter Asgard, ensuring it's safety throughout Odin's rule of King, whom Heimdall was fiercely loyal to.

Frost Giants Attack
"Heimdall, may we pass?" "Never has an enemy escaped my watch until this day. I want to know how it happened." "And tell no one where we have gone until we return."

- Thor and Heimdall

Despite his phenomenal ability however, Heimdall was unable to perceive an intrusion by several Frost Giants when they broke into the vaults of Odin. This same intrusion also sparked the ire of Odin's son Thor, who came to Heimdall, with several of his friends, seeking access to Jotunheim. Heimdall agreed to let them pass and accepted their request that he keep their movements secret.

Loki Takes the Throne
"You would defy the commands of Loki, our king? Break every oath you have taken as warriors, and commit treason to bring Thor back?" "Yes." "Good."

- Heimdall and Lady Sif

Later, with Thor banished and Odin fell into his Odinsleep, Loki placed himself on the throne as regent and demanded Heimdall's loyalty. Although he grudgingly accepted, Heimdall opted to only observe a literal interpretation of his vow to Loki and did not interfere when Sif and the Warriors Three used the Bifrost Bridge to reach Thor.

Fighting Loki
"For your act of treason, you are relieved of your duties as gatekeeper and no longer citizen of Asgard!" "Then I need no longer obey you!"

- Loki and Heimdall

Enraged, Loki dismissed Heimdall as his subject, thus releasing the protector of the Bifrost Bridge from his vow. Heimdall responded with an immediate attack with Hofund, but Loki froze him in a block of ice with the Casket of Ancient Winters before he could strike. Heimdall was frozen as Loki brought the Frost Giants, including Laufey, through the Bifrost. Locked in his icy prison, he was helpless to prevent Loki leading one of them into the city, but he was soon galvanized by the calls of Thor who was still trapped on Earth. Smashing free, he quickly cut down two Frost Giants who had been left to guard, and opened the Bifrost for Thor and his friends. Severely weakened, Heimdall could assist the adventurers no further as he collapsed from his wounds and had to be carried from his observatory to seek aid.

Losing the Bifrost
"So Earth is lost to us..." "No. There is always hope."

- Thor and Heimdall

After he left, Thor defeated Loki in a duel, at the cost of the Bifrost Bridge. The destruction of the bridge created a portal that sent Loki to an unknown area in space. Heimdall returned following the destruction of the observatory and when Thor asked if passage to Earth was lost, he showed him the Bifrost regenerating and replied, "No. There is still hope." When Thor asked Heimdall if he could see Jane Foster, Heimdall chuckled and told him that she was still looking for him.

War Between Realms
"The Marauders amass near Vanaheim. Thor's destruction of the Bifrost continues to shift the balance of power across the Nine Realms... and into the worlds beyond Yggdrasil."

- Heimdall With there being no way for the Asgardians to go to other Realms to help protect them, the other Realms of the universe fell into chaos. To keep the Asgardian leaders updated, Heimdall summoned Odin and Thor and warned them about the attacks. Thor, realizing that his friend Hogun would worry about his people in Vanaheim, chose to tell him about it. Thor asked Hogun to tell him if anything changes in the realms, especially Vanaheim.

Loki's Survival
Around a year after the Duel at the Bifrost Bridge, Frigga discovered Loki was in the Sanctuary. There, Loki was being trained by Thanos to rule Midgard. Soon Loki went to Midgard and started the Chitauri Invasion. With the Bifrost destroyed, Odin was forced to use dark energy to send Thor after Loki. With the help of the Avengers, Thor was able to arrest Loki and take him back to Asgard along with the Tesseract following the Battle of New York. Thor entrusted the Tesseract to Heimdall upon his return to Asgard. The all-seeing Asgardian then used it to repair the Bifrost Bridge.

End of the Marauders' War
"The universe hasn’t seen this marvel since before my watch began. Few can sense, even fewer can see it. A world that’s infected can be dangerous. It is truly beautiful."

- Heimdall to Thor

As Heimdall and Thor discussed Jane Foster, Heimdall lost track of her, causing Thor to travel to London to check on her. When Thor and Foster came across the Bifrost Bridge, Heimdall greeted them. Later, he witnessed as Fandral, Volstagg and the Einherjar returned from fighting the Marauders with their captives. Among the Marauders was Algrim.

Sacking of Asgard
"You’re not in Odin’s war council?" "The Bifrost is closed by your father’s orders. No one is to come or to go. We face an enemy that is invisible even to me. Of what use is a guardian such as that?"

- Thor and Heimdall

Simultaneously, as Algrim transformed into Kurse and conducted a prison break of the Asgardian Dungeons, Heimdall observed something strange flying pass him. He left his post on the Bifrost Bridge and chased it down. It was the lead Dark Elf Harrow trying to invisibly pass him. After destroying the ship, Heimdall used Hofund to activate the shield around Asgard.

Committing Treason
"You called me here on an urgent matter. What is it?" "Treason, my lord." "Whose?" "Mine."

- Odin and Heimdall

After the funeral of Frigga, Odin decreed that the Bifrost be shut down. Not needing to guard his post, Heimdall went to console Thor. As they spoke, Thor asked Heimdall to side with him as he hid Jane Foster, who was carrying the Aether. When Odin was told by Tyr that the mortal woman was missing, Odin looked disappointingly at Heimdall.

Observation
Heimdall saw a Kree arrive on Earth and, because of the enmity between the races, alerted the King. Heimdall opened the Bifrost Bridge and Sif was sent to investigate. After her assignment was completed, Sif called Heimdall to reopen the Bifrost so that she and the Kree Vin-Tak could go to Asgard.

The Search for Ultron
While the Avengers were searching for Ultron, Thor attempted to contact Heimdall to help look for Ultron. Heimdall did not respond to Thor, causing Thor to wounder if Heimdall had left his post, or was ordered not to respond.

Personality
Heimdall is a strong and loyal warrior, with a high sense of honor. Although being extremely powerful, even for an Asgardian, he loyally serves Odin, having swore an oath of faith to his king. However his true loyalty lies with the throne of Asgard, rather than Odin personally, as such when during Loki's reign, he did not personally let Sif and the Warriors Three pass onto Earth, but he secretly gave them his blessing. Then after Loki found out, he announced Heimdall as a traitor and no longer a citizen of Asgard. As a result, Heimdall attacked Loki, no longer bound to serve him. He was loyal enough to confess his disobedience (although he called it treachery) to Odin and surrendered.

Powers and Abilities
"Can you see her?" "Yes." "How is she?" "She searches for you."

- Thor and Heimdall

Like all Asgardians, he possesses superhuman physical attributes, such as strength, speed, stamina and reflexes, and he is an extremely powerful swordsman. He also has the power of nigh-omniscience, and his sight can extend itself to all Worlds (with Heimdall himself claiming to see 10 trillion souls from Asgard, but his senses can be deceived or averted, by both Loki and the Dark Elves. He is also blind to the realm where the Aether was hidden.

Powers
Heimdall possesses various superhuman attributes common among Asgardians. Heimdall possesses superhuman strength, speed, agility, reflexes, durability, and is extremely long-lived. Loki himself implies that his powers could equal or possibly exceed Odin.
 * Asgardian Physiology: As an Asgardian, Heimdall has superhuman abilities.
 * Superhuman Strength: Like all Asgardians, Heimdall is superhumanly strong and possesses greater physical strength than the average Asgardian male. He was able to break out from being frozen by Loki with the Casket of Ancient Winters, lift a Frost Giant with his sword and to destroy a Dark Elf Harrow using only his sword.
 * Superhuman Speed: Heimdall can move at extreme speeds. He managed to chase a Dark Elf Harrow, which can move extremely fast, and destroy it.
 * Superhuman Durability: Heimdall's body is much denser and much more resistant to physical harm than the body of a human being. He was capable of being frozen by Loki and showing no signs of injuries afterwards.
 * Regenerative Healing Factor: Despite his superhuman durability, Heimdall can be injured. However, his physiology allows him to heal at an accelerated rate.
 * Longevity: Like all Asgardians, Heimdall ages at a rate that is much slower than that of a human being. Even though he is over one thousand years old, he still looks like a young man by Earth standards.
 * Omni-Senses: Heimdall possesses sensory capabilities far beyond that of any Asgardians, which made him the gatekeeper to Asgard. His sight itself extends itself to all of the Nine Realms, and his hearing is so precise that he heard the Warriors Three and Sif conspiring against Loki before he decided to passively help them. Heimdall is able to hear other Asgardians calling him from other realms, such as Earth, Jotunheim or Vanaheim. When he uses his omni-senses, his eyes turn orange. Despite his phenomenal ability, however, his senses have been deceived for a degree by Loki and the Dark Elves.

Abilities

 * Master Combatant: Heimdall is a very capable combatant, having received training in swordsmanship. While normally using his sword to open the Bifrost Bridge, when using it in combat, Heimdall is powerful enough to defeat two Frost Giants when in a weakened state and defeat an entire Dark Elf Harrow with relative ease when at his prime.

Equipment

 * Hofund: Heimdall mainly uses his sword for opening the Bifrost Bridge, but the sword is also powerful enough to pierce the skin of a Frost Giant and the hull of a Dark Elven ship.
 * Gjallerhorn
 * Armor
 * First Set: Heimdall’s original armor was a gold metal chest plate that extended into shoulder guards over simple brown clothing. He also had a golden horned helmet. He wore black pants and gold boots and arm-bracers.
 * Second Set: Heimdall’s second armor was far more ornate with an illustration of Yggdrasil on his chest plate. His sleeves are gold and brown leather. He wore a gold and brown skirt over brown pants and detailed golden boots. Heimdall still wears a helmet that is the same shape as the first one but with patterns etched onto it.

Allies

 * Thor
 * Sif
 * Warriors Three
 * Hogun
 * Fandral
 * Volstagg
 * Odin - King
 * Frigga † - Queen
 * Tyr
 * Jane Foster

Enemies

 * Frost Giants
 * Laufey †
 * Loki - Former Ally and King turned Enemy
 * Dark Elves
 * Malekith †
 * Kurse †
 * Marauders

Video Game Only

 * Fire Demons - Enemies

Trivia

 * In the comics, Heimdall and Sif are brother and sister. Although this relationship has not been explored in the movies, concept art exists portraying Sif as black, confirming that this relationship was originally propped for Thor.
 * In, Heimdall guarded the Bifrost, which the Vikings believed rainbows came from. Heimdall was predicted to kill and be killed by Loki during the doomsday scenario of Ragnarök.
 * In Norse mythology, Heimdall has golden teeth. In the movies, he has golden eyes. Heimdall is also known as the whitest of gods, yet the actor that plays him has dark skin.
 * Heimdall’s armor design in Thor: The Dark World is meant to represent his watch over the Nine Realms. The tree represents Yggdrasil and the amber jewel, being the same color of his eyes, represents him looking over the realms.

Behind the Scenes

 * Heimdall is the only other Asgardian besides Thor to appear in theatrical films outside of the Thor franchise. Loki does not count, as he is a Frost Giant.