Eagle Vision, also known as Odin-Sight by Viking Assassins, is an extrasensory perception, or "sixth sense", that lies dormant within human beings as a result of interbreeding between ancient human beings and Isu. Amongst the Isu, who naturally possessed complete access to this sixth sense, it was known simply as Knowledge.
Though each average human holds the potential to utilize it through intense and very long training, some rare individuals display a greater concentration of the necessary Isu genes, and thus are more likely to naturally exhibit Eagle Vision as well as some of its more advanced variations.
Those who possess the gift are able to instinctively sense how people and objects relate to them, which manifests as a colored glow, much like an aura. Red indicates enemies or spilled blood, blue indicates allies, white indicates sources of information or hiding spots, and gold indicates targets or objects of interest. However, as Desmond Miles was—at least initially—unaware of Lucy Stillman's true affiliation with the Templar Order, it suggests the sixth sense is not entirely infallible.
When an individual masters Eagle Vision, the ability can evolve to the more advanced Eagle Sense. This stage heightens all the senses of its user, allowing them to detect the heartbeat of a target in the area, or even foresee a target's path. Some individuals also developed exotic variations of the gift; one application allowing its wielder to peer into the memories of their target upon killing them, while another one allowed a gifted individual to become a kind of lie detector, knowing when someone was lying or telling the truth to them. 
During the 5th century BCE, Myrrine, the daughter of Leonidas I of Sparta and the mother of the misthios Kassandra, taught her child that their family had a "gift" other people did not, describing it as an ability to "feel certain things happening around" them.
As an adult during the Peloponnesian War, Kassandra exploried Aletheia's simulation of Atlantis, where she learned that her "gift" represented a limited form of the Isu's sixth sense, "knowledge". During her time in Atlantis, Kassandra learned to commune with the Staff of Hermes Trismegistus and fully opened herself up to the Isus' sixth sense.
During the Viking expansion into England, the shieldmaiden Eivor Varinsdottir of the Raven Clan possessed Eagle Vision in addition to possessing a shared vision and sense with her raven, Sýnin. Dubbed "Odin's Sight", it allowed Eivor to locate and tag her enemies, and also allowed her to identify triquetra markings on numerous landmarks in England left behind by the Irish monk and Sage, Brendan of Clonfert.
The Assassin Altaïr Ibn-La'Ahad possessed Eagle Vision from an early age. His fellow Assassins in the Levantine Brotherhood knew of his special ability as well, and were the ones to dub it as "Eagle Vision". With it, Altaïr found himself able to read the emotions and intentions of all those around him, driving him to perfect the ability in secret. In his later life, he would make use of it during his many assassinations and investigations.
Altaïr's Eagle Vision proved particularly useful during his duel with his Mentor Al Mualim, who used an Apple of Eden to create phantoms of himself. With his ability, Altaïr was able to pinpoint the true Al Mualim from the crowd of illusions, and kill him.
Ezio Auditore da Firenze
Ezio Auditore da Firenze, much like Altaïr, possessed Eagle Vision and made use of it to locate hidden passages, as well as to predict the intentions of his allies and enemies. Additionally, he was also able to see the map hidden beneath the pages of Altaïr's Codex with it. Though it was never explicitly labeled "Eagle Vision", Giovanni Auditore da Firenze once referred to Ezio's ability as his "talent", and Salaì spoke of it as his "gift".
The Ottoman Assassins also knew of Ezio's ability, even before they had met him. When Piri Reis instructed him to use it to see through a smoke screen, Ezio pretended not to know what he was referring to, but Piri merely answered that "word gets around". Upon hearing this, Ezio asked that he keep the information to himself. Yusuf Tazim spoke of Ezio's skill as his "legendary senses", and Piri once mentioned that Ezio was a "special sort of man, with strange gifts". Ezio himself also admitted that his senses were "more finely tuned than most".
Giovanni Borgia also had Eagle Vision, which he used to locate and tail Francesco Vecellio through a crowd. He was also able to see images or drawings that were not really there, such as waves, arrows, and footprints; Francesco referred to Giovanni's ability as "us[ing his] other eyes".
Lo Sparviero could use the Eagle Vision to identify the Crows, Templar agents trained in counter-Assassin techniques who had uncanny disguise skills. He also could identify enemies, allies, targets, the Assassin insignia drawn with Leonardo da Vinci's special paint, and specific chests which held mission-critical contents. In Niccolò Machiavelli's journal, Machiavelli referred to Lo Sparviero's ability as his "special power".
Golden Age of Piracy
Mary Read, as Assassin in the West Indies Brotherhood, described Eagle Vision as the residue of life essence, attaching itself to every living thing around those who had what she called "the Sense". She claimed that every person could harness the Sense, but most either did not know they could or were unable to truly use the power until later in life. Edward Kenway claimed to have known the ability since childhood.
Much like Altaïr and Ezio, Edward could identify enemies, allies, and targets, but he could also 'tag' these people, allowing him to see their location when out of Eagle Vision, even through walls and other obstacles. He was also able to see hiding spots, such as hay bales and bushes, which would shine with golden and green glows, respectively.
The Colonial Assassin Shay Cormac possessed a form of Eagle Vision similar to Edward Kenway's, having the ability to mark potential targets. Following his defection to the Templar Order, Shay's Eagle Vision gained two new features. When not in use, the edges of his vision often gained a cloudy, pinkish hue, and ominous whispering could be heard, indicating that hidden gang leaders or Assassin stalkers were planning to ambush him. On activating it in the presence of hidden assailants, it would pinpoint the direction the attack would come from, and if Shay decided to investigate, would narrow its focus to the ambusher's exact location.
Haytham Kenway possessed Eagle Vision, though he was unable to mark specific targets. Haytham's son Ratonhnhaké:ton also possessed Eagle Vision which functioned in a similar manner. During his early years, Ratonhnhaké:ton learned how to use his gift to improve his tracking skills, and would use his gift to hunt animals. He continued to rely on the Eagle Vision upon joining the Assassin Order, during his hunt for the Colonial Templars.
One notable instance of this presented itself while Ratonhnhaké:ton hunted down one of the pieces of Captain William Kidd's map, contained at Edinburgh Castle in Jamaica, where he used his Eagle Vision to examine clues in order to reconstruct the murder of one of Lewis Hutchinson's victims, later finding the man's body and retrieving the map piece.
Some time during the 1780s, Ratonhnhaké:ton married a native woman and had a son and two daughters, and soon recognized that one of his girls, Io:nhiòte, had untapped talent with Eagle Vision. On a hunting trip in April 1796, Io:nhiòte fell from a small cliff drop and sprained her ankle. As Connor left to find water to bring the swelling down in Io:nhiòte's leg, she noticed fresh wolf tracks and tried to warn her father, but he was too far away to hear her. Panicking, she saw an eagle in the sky and inexplicably connected with it to fly over her father and screech a warning before the wolf leapt at him. After killing the wolf, Ratonhnhaké:ton returned and was amazed that Io:nhiòte knew of the wolf attack.
Aveline de Grandpré was one of the few known female Assassins to possess Eagle Vision, which functioned similarly to Connor's, though certain things possessed purple highlights, such as blood and wanted posters. Much like Connor, she could use Eagle Vision to examine clues to reconstruct past events and crimes, aiding her in investigations and finding targets. By the year 1784, Aveline had gained the ability to mark targets with Eagle Vision, similar to Adéwalé and Edward Kenway. It is unknown whether Connor or Haytham also developed this ability.
The French Assassin Arno Dorian possessed three variations of Eagle Vision during the French Revolution. The first was Eagle Pulse, a momentary vision that soon faded away. The second was more akin to Ezio Auditore's Eagle Sense, a longer lasting effect. The third version was Communal Sense, allowing Arno's fellow Assassins to see what he saw, within a limited range.
Arno could only view the memories of his victims, rather than being able to converse with them directly. He also had the ability to read the paths that guards would take, much like Eagle Sense, but only could fully utilize this skill once he read the paths on a map. Lastly, this skill appears to have been connected with his auditory system, allowing him to hear conversations from far away with perfect clarity once he achieved a high enough vantage point and focused in on the locations. He appeared to be able to maintain great focus while using it, as even while climbing, shooting, or killing, the pulse would sustain. Even when heavily consuming alcohol, he could still use Eagle Pulse, though it caused him pain when used.
The twins Jacob and Evie Frye possessed Eagle Vision, and while the exact date of when they learned of the ability is unspecified, both had been able to use it since they were around 20 years old. Their form of the vision caused very little distortion in sight, causing them to see in muted tones of black and white. When using this sense, they could see and "mark" targets from very long distances, and even identify individuals by names, objectives, and opportunities to aid them in assassinations. Targets showed up in yellow, allies in green, enemy Templars and Blighters in red, and members of the Metropolitan Police Service in blue. Unlike other Assassins, both twins could only use Eagle Vision when stationary or moving no faster than a walking pace.
In one notable instance, Evie Frye was able to solve a puzzle left by Edward Kenway at his home because unlike their Templar antagonists, Evie was able to see with the Eagle Vision the clues left behind by Edward.
The twins also utilized Eagle Vision during criminal investigations, such as a series of murders tasked to them by Henry Raymond in 1868, and the Whitechapel murders committed by Jack the Ripper in 1888. Through the sense, the twins were able to identify clues as well as mark their own observations and trajectories based on the information acquired.
Jack the Ripper also possessed Eagle Vision, however, his vision became unstable upon activation, and he regularly hallucinated words in the air related to his objectives.
- "Try using that special sight you learned from Altaïr."
- ―Lucy Stillman to Desmond Miles in the Sanctuary, 2012.[src]
By using the Animus to follow the memories of his ancestors, Desmond Miles also gained the ability to use Eagle Vision, likely as a result of the Bleeding Effect. Through it, he was able to see Lucy Stillman and Warren Vidic shimmering with a blue and red aura, respectively. He was also able to use this ability to see the cryptic messages that Subject 16, Clay Kaczmarek, had written in the Abstergo laboratory with his own blood.
Clay also hid a series of Glyphs within the rendered Animus environment, which needed to be scanned with Eagle Vision to be unlocked. Similarly, the Rifts that the Glyph puzzles led to also needed Eagle Vision to be both seen and accessed.
During his escape from Abstergo Industries, Desmond found another application for his newly acquired power. Much like thermal vision, he used it to discover the code of a keypad, by seeing the heat signature of the fingerprints left upon the correct numbers.
Later, upon reaching Monteriggioni, Desmond was also able to use Eagle Vision to see a message that Ezio had left upon the wall of the Sanctuary stairwell, which bore the password to the Colosseum Vault. While traveling through the Colosseum to the Santa Maria in Aracoeli, Desmond used Eagle Vision to locate a series of switches to open hidden entrances. He also made use of it to see the proper sequence of levers he needed to activate, in order to access the Apple of Eden hidden inside.
The Abstergo recruits who participated in the Animi Training Program were also granted an ability named Templar Vision. This rendered ability mimicked Eagle Vision, and was able to be used for approximately 3.5 seconds.
When he traveled to Osaka, Japan on 4 December 2013 seeing aid from the local Brotherhood, Gavin Banks used his Eagle Vision to determine that the yakuza, not Abstergo, had killed the Assassin cell in the city, though this invariably taxed his energy.
Mastering Eagle Vision led to the user being granted Eagle Sense. A more heightened form of Eagle Vision, it allowed one to focus on a target and intuitively approximately where they had gone, or inversely, where they would go, even going so far as to be able to sense the presence of stalkers and when they would strike. This was particularly helpful in tailing a target, or detecting the path a guard would take, in order to set up a bomb or lay an ambush.
With Eagle Sense, Ezio was also able to pick up cold trails, or locate disguised enemies. However, for the latter, he was required to concentrate harder and scrutinize people individually, rather than as a crowd. Ezio also once used his Eagle Sense to follow the scent vapors of datura, and to diagnose an injured mercenary by listening to his heartbeat. As such, the latter technique allowed him to conclude that the man was alive but weak, and likely affected by some form of poison.
Throughout history, there have been four individuals who were known to have had an advanced form of Eagle Vision manifesting as a sort of reversal to Arno's Communal Sense, whereby they were able to telepathically see and hear through the senses of avians, particularly eagles. The four known individuals who had this ability were the Spartan misthios Kassandra during the Peloponnesian War in ancient Greece through her eagle, Ikaros; Bayek of Siwa, a Medjay and co-founder of the Hidden Ones through his eagle, Senu; the Viking shieldmaiden Eivor Varinsdottir with her pet raven Sýnin; and Io:nhiòte, the daughter of the Colonial Assassin Ratonhnhaké:ton.
- Assassin's Creed
- An Assassin guard could be seen glowing red in Eagle Vision at the Kingdom entrance to Masyaf, but he reacted in normal guard behavior. This guard was Jamal, an Assassin who aided Masun in betraying the Brotherhood, and was originally intended to have been a target. However, the sequence where Altaïr assassinated him was cut, leaving him as a minor Easter egg.
- In the original Assassin's Creed, movement was restricted while using Eagle Vision, and Altaïr was required to be at maximum synchronization. These requirements were removed in most of the succeeding games.
- In Assassin's Creed, Eagle Vision was explicitly said to actually be the Animus' visualization of the Assassin's observational skills, and not a supernatural ability the Assassins actually possessed.
- Assassin's Creed II
- The users of Eagle Vision saw themselves marked with blue.
- At the beginning of the game, while playing as Desmond in the hideout, he could see equipment shine blue in Eagle Vision. This indicated that they could be used for freerunning purposes.
- Lucy made a reference to the ability by saying "Open your eyes, Desmond," when Desmond asked her how to find the sensors for the hideout's defense system, which she had tasked him to switch on.
- In some memories in both Assassin's Creed II and Assassin's Creed: Brotherhood, water was shown to be glowing white like hiding spots when Eagle Vision was activated.
- Assassin's Creed: Brotherhood
- When traveling through Rome, Eagle Vision could be used to mark flags, feathers or treasure chests on the map.
- While using Eagle Vision and roaming Monteriggioni as Desmond, a red trail was visible that led from the fountain with the Assassin insignia to the door of Mario Auditore's study. The trail was colored similarly to the blood glyphs of Subject 16, and appeared to be made up of many footprints.
- When outside of the Animus, there was sometimes a pause that caused allies to glow gold for a few seconds.
- Unlike in Assassins Creed II, enemies and allies did not glow their standard colors after they died, and would appear grey like civilians and inanimate objects.
- If Eagle Vision was activated when Ezio was dressed as a Borgia guard captain in the memory "When in Rome...", the armor would glow red, though Ezio himself would still be marked with blue.
- Unlike Eagle Vision, Templar Vision marked targets with blue rather than with gold, since they were hunting other Templars and could be considered allies within a contained session.
- Assassin's Creed: Revelations
- During Ezio's pilgrimage and Altaïr's return from exile, ghostly images from Altaïr's past could be seen in Masyaf.
- Unlike regular enemies, the paths of officials and the two guards accompanying them could not be tracked with Eagle Sense.
- Assassin's Creed III
- In the Grand Temple, Desmond, Rebecca Crane, Shaun Hastings and William Miles were not highlighted at all in Eagle Vision.
- Assassin's Creed IV: Black Flag
- Similar to the way it functioned in the original Assassin's Creed, Eagle Vision could not be used while moving in high profile.
- Corpses of enemies that have not yet been looted would glow white.
- A mini-game in the Assassin's Creed room of PlayStation Home featured an Eagle Vision puzzle that, when completed, opened up the Hideout.
- An issue of Nintendo Power stated that the Wii U tablet controller could be used as an alternate view for Eagle Vision in Assassin's Creed III, using the built-in accelerometer to control the camera view.
- Ezio's Eagle Sense functioned in a clairvoyant manner.
- Desmond, unlike his ancestors, didn't naturally possess a practical form of Eagle Vision, but rather he possessed it as a dormant trait, like most humans, despite having a significantly high concentration of precursor genes.
- In Watch Dogs 2, another Ubisoft game, the NetHack ability is very similar to Eagle Vision.
- In Thief, a game developed by Eidos Montréal and published by Square Enix, the main character Garrett possesses an ability known as "Focus", which not only works similarly to Eagle Vision, but it also enhances his thieving and combat skills.
- Assassin's Creed: Last Descendants – Fate of the Gods – 
- Assassin's Creed: Odyssey – The Fate of Atlantis: Judgment of Atlantis – Welcome Home
- Assassin's Creed IV: Black Flag – This Old Cove
- Assassin's Creed
- Assassin's Creed – Modern day
- Assassin's Creed II – Modern day
- Assassin's Creed: Brotherhood – Modern day
- Assassin's Creed: Revelations – Modern day
- Assassin's Creed: Revelations – Database: Ezio Auditore da Firenze
- Assassin's Creed: Unity
- Assassin's Creed: Odyssey – Memories Awoken
- Assassin's Creed: Odyssey – The Fate of Atlantis: Judgment of Atlantis
- Assassin's Creed: Valhalla
- Assassin's Creed: Revelations – Database: Altaïr Ibn-La'Ahad
- Assassin's Creed – Assassination (Al Mualim)
- Assassin's Creed II
- Assassin's Creed II – X Marks the Spot
- Assassin's Creed II – Jailbird
- Assassin's Creed: Brotherhood – The Da Vinci Disappearance – Decoding Da Vinci
- Assassin's Creed: Revelations – Piri Reis: Smoke Screen
- Assassin's Creed: Revelations – The Trickster, Part 2
- Assassin's Creed II – Database: La Volpe
- Assassin's Creed: Project Legacy – Rome: Chapter 2 – Giovanni Borgia
- Assassin's Creed: Identity
- Assassin's Creed: Identity – Niccolò Machiavelli's journal: "Entry Three: Vengeful Eyes"
- Assassin's Creed IV: Black Flag – Nothing Is True...
- Assassin's Creed IV: Black Flag
- Assassin's Creed IV: Black Flag – Freedom Cry
- Assassin's Creed: Rogue
- Assassin's Creed III
- Assassin's Creed III – Hunting Lessons
- Assassin's Creed III – The Mad Doctor's Castle
- Assassin's Creed: Reflections – Issue #04
- Assassin's Creed III: Liberation
- Assassin's Creed IV: Black Flag – Aveline
- Assassin's Creed: Unity – Bottom of the Barrel
- Assassin's Creed: Syndicate
- Assassin's Creed: Syndicate – Playing It by Ear
- Assassin's Creed: Syndicate – Jack the Ripper
- Assassin's Creed: Brotherhood – Multiplayer
- Assassin's Creed: Initiates – Surveillance: "Osaka He Youkoso"
- Assassin's Creed: Revelations – Unfortunate Son