The Immortality Spell is an extremely powerful spell used to transform a mortal person into one of four immortal creatures; either a true immortal, like Silas and Amara, an Original vampire, like the Mikaelson Family, an Enhanced Original vampire, like Alaric Saltzman, or an Upgraded Original vampire, like Lucien Castle and Marcel Gerard.
The spell was originally conceived by "one of the most powerful witches of all time," Qetsiyah. However, after Silas manipulated Qetsiyah into creating a spell for immortality, he betrayed her by giving the elixir to his true love Amara, both becoming the world's first and only true immortals. Approximately one thousand years later, another powerful witch named Esther modified Qetsiyah's original spell as a solution to protect her family from werewolves and other harm. However, after she cast the spell, the Spirits retaliated against her, and she unknowingly transformed them into the first vampires. Esther performed the spell one thousand years later to make Alaric Saltzman the first Enhanced Original Vampire with powers stronger than the Originals for the purpose of hunting down the Originals and killing them with the indestructible White Oak Stake. A few years later Vincent Griffith was forced to cast an altered spell to create a serum that would turn the intended subjects into Upgraded Original vampires, prophesied as "the Beast"; Lucien, and then Marcel, eventually became 'Beasts', gaining superior strength and speed over that of the Originals, including Klaus, the Original Hybrid. However, the Beasts possess an additional power over an Enhanced Original, like that of Alaric, a venomous bite capable of killing an Originals without the need of a White Oak Stake. This was incorporated into the spell that made the Originals, a spell that Lucien had a coven of witches reverse engineer over a length of time. This additional power is superior to the Enhanced Original given its lethality to kill Originals without white Oak.