User may require continued offerings and sacrifice of some kind in order to continue existing.
Whatever was sacrificed could influence the user in question, be it their body, mind, etc.
All Humans (Prometheus)
Steven Universe (Steven Universe)
Summoning Jutsu: Reanimation/Impure World Reincarnation (Naruto)
Justus (Shakugan no Shana)
Necromorphs (Dead Space)
Killabilly (Lollipop Chainsaw)
Diablo (Diablo); as the Prime Evil
The Engineer (Prometheus) who first offered his own life to bring a new life into creation was the one who brought humanity into existence, though that makes all of humanity a product of his sacrifice.
Rose Quartz willingly sacrificed her physical form to bring her son Steven Universe (Steven Universe) into the world.
Necromorphs (Dead Space) are a race of undead flesh-creatures that are spawned from the death of those infected by their pathogens.
Kilabilly (Lollipop Chansaw) is a massive, undead entity that is created from the dead-bodies of the Dark Purveyers, thousands of other zombies and the summoner, earning his nickname as "the Zombie of Zombies."
Those summoned via the Impure World Reincarnation (Naruto) are corpse bodies created via a live sacrifice.
Justus (Shakugan No Shana) was born when Johann & Pheles sacrificed their power of existence in order to bring him into the world.
Diablo (Diablo) became the Prime Evil, the embodiment of all seven Great Evils in one being, through the use of the Black Soulstone and the sacrifice of Leah, the daughter that he had with the witch Adria.