"For the perishable must be clothed with the imperishable, and the mortal with immortality."
― 1 Corinthians 15:53
"I’m only gonna say this once so listen carefully, Trafalgar D. Water Law. Perform the Perpetual Youth Surgery which is the ultimate Op-Op technique on me and…die! In exchange, I’ll grant your wish, whatever it is."
The Staff of Hermes Trismegistus (Assassin's Creed) was a Piece of Eden that, amongst others, could grant its holder immortality.
Zed (Code:Breaker) using his Death ability to materialize life and retrieve it, and immortalizing anyone who has their "life" extracted via this manner.
Shenron (Dragon Ball) can grant immortality to one who wishes it. Only Garlic Jr. succeeds in making the wish, as all others who tried are impeded by various circumstances.
Utsuro (Gintama) granted Oboro immortality by giving him immortal-enriched blood, allowing the child to survive even fatal wounds. However, Oboro's mortal flesh is breaking down from the blood's power in the long term, and its immortal attributes are only prolonging his suffering.
The Dog Talisman (Jackie Chan Adventure) grants the power of immortality, rendering its wielder completely immune and resistant to otherwise lethal attacks/injuries and also restores youthful energy.
The Yin Blade (Lego Ninjago: Masters of Spinjitzu) could grant immortality with the usage of Dark Magic. However, extreme usage of it can result in the user becoming a ghost.