Immortality

is the status of possessing eternal life. Depending on the individual, it can either be perpetual youth, the inability to be permanently killed, or complete invincibility.
==Characteristics==
In the case of humans, it is said complete deathlessness does not exist.Fate/Apocrypha Volume 1: Apocrypha: Great Holy Grail War - Chapter 4 While conditions of invulnerability can exist among the many legends of human heroes, even human-based Heroic Spirits are unable to go beyond the bounds of being a human being and attain truly immortal bodies, such existences being outside of common sense not normally able to manifest as Servants. Even with heroes said to have immortal bodies, it is assumed there is always a stipulation of "However, there is one exception" in all immortality legends.Fate/Apocrypha Volume 2: Round Dance of Black / Festival of Red - Chapter 3
The Third Magic is a Magic that realizes true immortality by making the soul into a high-dimensional planar being capable of interacting with the material world as a mental body without having to return to Akasha.
According to Mario Gallo Bestino, most of the Dead Apostle Ancestors' Principles originate from something that the individual vampires studied when they were human, and after they became vampiress, such Principles become their "purpose for living" and path to obtaining true immortality.Tsukihime -A piece of blue glass moon- - Moon Princess route - Day 10: "Vermillion, Crimson Moon I"
Entities without a Concept of Death are also immortal.
:See also Concept of Death.
===Immortal Killers===
*Harpe has the trait of , which is a divine ability that nullifies the "undying attribute" of immortals and inflicts wounds that cannot be restored by any methods other than healing in accordance to the natural laws.Fate/hollow ataraxia - 10/08 - Emiya's - Mirror of KibisisFate/Grand Order material IV - Medusa (Lancer), p.342-351, translated by castor212, Beast's LairFate/Grand Order - Babylonia: Absolute Demonic Front - Section 15: Decisive Battle 
*Black Barrel is a "Conceptual Weapon of natural life-span", capable of imposing the notion of limited life-span into the body of near-immortal creatures.
*Seventh Holy Scripture (Remake) is no doubt, a surefire "Immortal Killer".
==Examples of immortality==
*Achilles — His gift of immortality from having been blessed and exalted by the Olympian Gods, granted to his entire body, excluding his heel, protecting him from all ill will and killing intent. It takes the form of the Noble Phantasm Andreias Amarantos.
*Ahasuerus — Complete immortality, having lived since the time of Christ. Even if he were to be cut up into pieces or shot full of bullets, he still wouldn't be able to die.
*Amakusa Shirou Tokisada — Received eternal youth after being incarnated thanks to his Noble Phantasm Left Hand - Xanadu Matrix.Fate/Apocrypha Volume 3: Triumphal Return of the Saint - Prologue
*Artoria Pendragon - The Holy Swords Caliburn and Excalibur stopped Artoria's body from aging.Fate/stay night - Fate route - Day 11: DragonSlay - The king's memoriesFate/stay night - Fate route - Day 12: Interval Level4 - The king's memoriesGarden of Avalon - "A Tale of Knights: Lancelot" Even after having lost Avalon, Excalibur still continued to grant Artoria special regenerative properties. Had Artoria not embraced her fate and given away Excalibur to Bedivere after having been fatally wounded by Mordred, she could have continued living for thousands of years.Fate/Grand Order - Camelot: The Sacred Round Table Realm - Section 17: Replica
*Alice Kuonji — Complete immortality and eternal youth, as while Aoko Aozaki ages over time, Alice cannot. Alice cannot be killed except under very specific conditions. If someone attacks her with animosity, fear, nature, or even random chance, she will resurrect no matter how badly she is injured. However if she is attacked with an act motivated by love, this resurrection will not activate.Fate/Grand Order - Alice Kuonji's profile translated by Petrikow at Beast's Lair
*Aoko Aozaki — Eternal youth, as Aoko stopped aging after 20.
*April – Complete immortality, as a Witch, she cannot die.
*Ashiya Douman — Engraves his Saint Graph in countless Shikigami bodies, rendering him able to control them remotely and scatter them at will, gaining a form of immortality through his ritual Life Continuation.Fate/Grand Order: Cosmos in the Lostbelt - Yuga Kshetra: The Black Final God - Section 19: The Final Dark God
*Brishisan — Has existed for nearly 3000 years without issue, implying he is something other than human, referred to by Touko Aozaki as a "Vampire knockoff" despite not being a Dead Apostle.Clock Tower 2015 - 03 Autumn - Suburb of London - Clock Tower Eleventh District
*Calamity Jane and Sigurd the Dragon-slayer Sword - After defeating Ashtart Origin, they were "rewarded" with eternal life until she awakened again.Fate/Grand Order - Saber Wars II - To the Beginning of Space, To the Beginning of Space
*Caenis — Thanks to her Poseidon Blessing Noble Phantasm, Caenis is invulnerable as long as she is in the Ocean.
*Camazotz (Lostbelt) — Camazotz's Imperishability Authority makes him completely unkillable. It can only be nullified if Camazotz is forced to remember his past.
*Chiron — Complete immortality, rendering him unable to die despite being in constant pain from Hydra poison. The immortality itself is able to be removed by the Gods and granted to another.Fate/Apocrypha Volume 1: Apocrypha: Great Holy Grail War - Chapter 1
*Ciel (Remake) - Complete immortality so long as Michael Roa Valdamjong (Remake) is alive, due to the World recognizing them as the same individual.Tsukihime - Near Side: Ciel's route - 11/ MirageTsukihime -A piece of blue glass moon- - Rainbow in the Night route - Day 10: "Bow of the Skies II"
*Darius Ainsworth — Complete immortality, having created his own style of Flash Air in order to record and store dozens of years of his life, the concept of "Darius", within Pandora's Box, as it contains a place that is not bound by the same rules of the World and so the record of his soul won't suffer decay inside it. This has the side-effect of making Darius unable to die unless the Pithos is opened, making him immortal.Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 65.2: "Tactility Of The Planet"
*Dead Apostles — Eternal youthTsukihime - Near Side: Arcueid's route - 3/ The Black Beast I and the Curse of Restoration that allows them to regenerate from injuries, but require the blood of humans to supplement and upkeep their unlife.Tsukihime - Near Side: Ciel's route - 6/ Bow in the Sky I
*Demeter (Lostbelt) — Demeter possesses Authority over the harvest, in other words, production and regeneration. Theoretically, she can regenerate from any amount of damage, making it impossible to completely destroy her. This immortality can be passed down to others with her Klironomia. Poseidon's own Authority can suppress its effects, due to Poseidon also wielding Authority over the land.
*Erika Ainsworth — Complete immortality until she opens Pandora's Box as her "death" is contained in the box.Fate/kaleid liner PRISMA☆ILLYA 3rei!! - Chapter 53.3: "The Nameless Girl"
*Fairies — Essentially immortal and do not have the same lifespan as humans or animals. 
*Francesca Prelati — Resurrects in a new body after death, which can be either male like her original body, or female.Fate/strange Fake Volume 3 - Prologue VIII: "The Star Performers' Feast (Part 1)" Her exact methods are unknown, but she has persisted without apparent side effects for hundreds of years, and possesses "secret organs" within her chest that she displays to Orlando Reeve.Fate/strange Fake Volume 2 - Chapter 6: Day 1, Noon "Two Archers and..."
*Goddess Rhongomyniad
*Goetia — As long as the Temple remains in Goetia's possession, the 72 Pillars will continuously revive, thus he is immortal; relinquishing possession of it causes the Pillars to be undone and makes Goetia vulnerable.Fate/Grand Order - Solomon: The Grand Time Temple - Section 12: The Future
*Heracles — His Noble Phantasm God Hand, a blessing of the Gods representing immortality, as well as being a curse, that was granted to him for completing his in life.
*Kischur Zelretch Schweinorg — In Tsukihime Worlds, he is a Dead Apostle and one of The Twenty-seven Dead Apostle Ancestors (Remake). In Fate Worlds, he managed to achieve immortality without being a Dead Apostle.
*Kundry — She is described as being cursed with immortality, but in a way that she would wander from world to world by reincarnating while keeping her memories until she would find her one true love. Because of this unique sort of immortality, Kundry as a Servant can remember individual summonings unlike how most Servants forget each time they are summoned.Fate/Requiem Volume 1: The Boy Among the Stars - Prologue
*Justeaze Lizrich von Einzbern — Eternal youth, however her body was so frail it would take little to kill her.
*Lugh Beowulf — A naturally immortal Elemental who exists as a materialized soul similar to the products of the Third Magic.
*Merlin (Prototype) — Complete immortality, having transcended death due to being trapped within Avalon. 
*Michael Roa Valdamjong (Remake) - In addition to being a Dead Apostle, he is able to completely persist beyond death so long as human beings exist in the world,Tsukihime - Near Side: Arcueid's route - 10/ Vermilion Crimson Moon IITsukihime - Near Side: Ciel's route - 7/ Bow in the Sky II by taking them as host bodies through Reincarnation. In the original Tsukihime, he loses more of his identity with each soul he assimilates into his own, but in the continuity of Tsukihime Remake, this is not the case.
*Olympian Soldier — Demeter Klironomia makes them immortal.
*Ozymandias — A divine protection of Ramesseum Tentyris that grants immortality to Ozymandias and his Guardian Beasts, making total destruction of both the temple and Ozymandias himself necessary to defeat him.Fate/Prototype: Fragments of Sky Silver Volume 4 "Dear My Hero Arc" - Chapter 3 Part 2-A and 2-B (translated by PhoenixRising)
*Paracelsus — While not immortal himself, he is able to create the Philosopher's Stone with a high degree of purity, such that it can grant someone a limited form of immortality.Fate/Grand Order material III — Profile of Paracelsus von Hohenheim, translated by Kinalvin at Reddit.
*Riesbyfe Stridberg - Eternal youth through Gamaliel's ability to halt the user's aging.
*Scáthach - Complete immortality, having turned halfway into a Divine Spirit at the end of a long time, became an immortal existence. She can no longer die as a person.Fate/hollow ataraxia- 10/08 - Streets - That past is alreadyFate/Grand Order material II - Scáthach, p.282-297, translated by Kinalvin at Reddit.Fate/Grand Order Profile of Scáthach, translated by Master of Chaos at Beast's Lair.
*Servants (Servant Universe) - Normally, there is no such thing as lasting death in the Servant Universe. Servants that disappear eventually respawn randomly in another part of the universe, or reincarnate in a new body, or even interfere in a Parallel World. That is what it means for a Soul to be tangible.Fate/Grand Order - Saber Wars II - To the Beginning of Space, Goddess Scripture 4 "Goddesses and Ancient Shrines"
*Souren Araya — His Origin of "Stillness" has made him extremely difficult to kill, since something that is already "still" supposedly cannot be killed. Touko believes that he differs from Magi who would fade away should they ever touch the Root, and that at least some shade of himself will remain in the world and possibly bring great destruction. He is effectively immortal in a sense due to his consciousness surviving even if his body should rot and crumble to dust, and he has reconstituted himself after such a death from aging several times, having taken new physical bodies each time.
*Stheno and Euryale - Eternal youth, never aging unlike the other Gods of their pantheon that needed to consume Golden Apples to maintain their eternal lives.Fate/hollow ataraxia - 10/10 - Emiya's - Gorgon's cellar
*Touko Aozaki - Creates Puppet copies of her body that are exactly identical to her original body. Exists in a state of superposition between all her copies at once, and will "wake up" in a new body if her current one is killed. Appears to have eternal youth in addition to this, and is speculated by Francesca Prelati to have attained some form of the Third Magic.
*True Ancestors - Eternal youth and the Curse of Restoration, but do not need to consume blood to stay alive like the Dead Apostles.
*World of Fate/Requiem - All humans living in the world except Erice Utsumi are immortal. Chitose Manazuru's wish on the Holy Grail had brought immortality to the masses. The principal causes of death in the old world – biological factors such as aging, genetic degradation, infectious diseases, viruses and malignant cancers – had all been conquered. However, people can still be murdered. By expending Command Spells, one could even manipulate their biological age. In Mosaic City, one of humanity’s oldest, dearest wishes – eternal youth – had been realized.Fate/Requiem Volume 1: The Boy Among the Stars - Chapter 1
*Zouken Matou - Became a swarm of Crest Worms. As time went on, his method of immortality caused his soul to decay, leading to him needing to consume human flesh similar to a Dead Apostle, and causing him to appear as a wizened old man.Fate/stay night - Heaven's Feel route - Day 7: dialogue lost loop - Interlude 7-2: Madness
==References==
Category:Magecraft terminology
Category:Functions of Magic
Category:Third Magic
Category:Terminology in Tsukihime
Category:Terminology in Tsukihime Remake
Category:Terminology in Fate/Apocrypha
Category:Terminology in Fate/stay night
Category:Terminology in Fate/strange Fake
Category:Terminology in Mahoutsukai no Yoru
Category:Terminology in Kara no Kyoukai
Category:Terminology in Fate/kaleid liner PRISMA☆ILLYA
Category:Terminology in Lord El-Melloi II
Category:Terminology in Fate/Requiem