Immortality

Immortality is the ability to live forever or avoid permanent death, either due to inherent abilities or use of external methods to prolong one's life indefinitely. Various life states throughout The Sims possess this ability, and multiple methods exist to achieve immortality.

Immortal life states

There are many life states throughout the series which are inherently immortal, and possess the capability to live forever unless killed through unnatural means.

The Sims

• Ghosts cannot be killed, as they are already dead.
• Most NPCs, such as the firefighter, cannot be killed.

The Sims 2

• As in The Sims ghosts cannot be killed, as they are already dead.
• In The Sims 2: University, zombies are unable to age past the Adult life stage, and therefore possess the potential to "live" forever.
• In The Sims 2: Nightlife, vampires, much like zombies, cannot age, although they can be killed by other means, notably their vulnerability to sunlight.
• In The Sims 2: Open for Business, Servos do not age, and can only be killed by a falling satellite, being eaten by the Cowplant, or by running with scissors.

The Sims 3

• Much like in the previous two Sims games, ghosts are still essentially immortal, although they can be permanently removed from the game if their tombstone is deleted or they are made playable and choose to Return to the Netherworld.
• In The Sims 3: Late Night, while still possessing greatly augmented lifespans, vampires are no longer immortal and can die of old age, although if The Sims 3: Supernatural is installed they can acquire the Immortal lifetime reward to make them completely ageless and immune to the sunlight.
• In The Sims 3: Into the Future, Plumbots, much like Servos, cannot die of old age and can only be killed by a falling meteor, although some store items such as the Cowplant or the Door of Life And Death are capable of killing Plumbots.
• Though a trait and not a life state, Sims with the Unlucky trait cannot die of anything other than old age (the Grim Reaper will immediately resurrect them due to their death being too amusing and predictable), but if they drink the Age Freeze potion or have the Immortal Lifetime reward, they become ageless and lose the ability to die from old age. This effectively renders them immortal, as the people who are instantly revived in the case of an accidental death lose the ability to die naturally.

The Sims 4

• Ghosts remain immortal, but can be killed if they are revived first.
• In The Sims 4: Vampires, much like in The Sims 2: Nightlife, vampires stop aging once they become a young adult.
• In The Sims 4: Realm of Magic, although spellcasters aren't immortal, they can brew a potion of rejuvenation or a potion of immortality; which only spellcasters can create.
• In The Sims 4: Discover University, Servos do not age, and can only be killed by catastrophic meltdown, or being eaten by the Cowplant.
• While not technically life states, Baby Ariel, Grim Reaper, and Father Winter all have traits that render them immune to death in every form.
• In The Sims 4: Werewolves, Apex werewolves can take the Immortal Wolf ability to live forever.

Methods of becoming immortal

The Sims 2

• Sims with a high enough Aspiration Meter can drink the Elixir of Life and continuously purchase resupplies of the elixir when they run out, effectively rendering themselves ageless. However, this method not only requires the Sim to maintain a high aspiration bar, but also requires the Sim or another Sim in the household to be able to afford replacement elixirs each time one runs out.
• Similarly to the above method, if University is installed, a Sim can use the elixir produced by the Cowplant to achieve the same effect. This has the benefit of not requiring a certain aspiration level but comes with the drawback of requiring that other Sims be sacrificed to the Cowplant on a regular basis.
• If University is installed, Sims can be brought back to life through use of the Resurrect-O-Nomitron by another Sim. Since this process can be repeated an indefinite number of times, any household can avoid permanent death using this method, as long as it can afford to pay the Grim Reaper. A deceased Sim can also be revived as a zombie to prevent them from aging, although it is questionable if an immortal Sim would prefer such an existence.
• If Nightlife is installed, becoming a Vampire will make a Sim ageless but extremely vulnerable to sunlight.

The Sims 3

• Ambrosia can be used as an effective means of prolonging a Sim's life, as its consumption will reset a Sim to the beginning of their life stage and add eight days to their lifespan. However, preparing Ambrosia requires rare ingredients that generally necessitate a high skill level to obtain, as well as the $12,000 recipe and a level 10 Cooking skill.
• A Death Flower can be kept in a Sim's inventory as a means to prevent permanent death. When a Sim carrying a Death Flower dies, the flower will be presented to the Grim Reaper, who will excitedly accept it and restore the dead Sim to life. This applies no matter how the Sim died, and a sufficient supply can render a Sim completely immortal.
• Unlucky Sims are unable to die accidentally, as the Grim Reaper finds their misfortune too amusing and will simply revive them, providing a partial form of immortality.
• If Generations is installed, Sims with a sufficiently high Logic skill are capable of creating a Young Again potion, which will restore a Sim to the beginning of their Young Adult life stage. The potion can also be purchased as a lifetime reward.
• The above expansion pack also includes an Age Freeze potion as a lifetime reward. Drinking the potion will render the Sim ageless, however if the Sim dies accidentally and is revived the effects of the potion will disappear and the Sim will age normally.
• If Supernatural is installed, Sims can obtain the Fountain of Youth Elixir from an elixir consignment store, or brew it themselves with sufficient Alchemy skill. It has the same effect as the Young Again Potion shown above.
• The Door of Life And Death can be used by any Sim to revive deceased Sims continuously, although this method will reincarnate the Sim with a randomized appearance and gender, and sever the Sim's previous relationships as well as a portion of their skills. This method also requires that the reincarnated Sim be raised from babyhood back to adulthood, so it may seem undesirable to some players.
• If purchased from the Store, the Cowplant can be used like the previous games to prolong a Sim's life. However, the Cowplant's elixir has the same effect as Ambrosia, and will reset a Sim to the beginning of their current life and adding the Divine Meal moodlet.

The Sims 4

• Ambrosia functions much like in the previous game but requires more skills to prepare, and can be used to prolong a Sim's life indefinitely.
• A Potion of Youth can be purchased as an aspiration reward, and can be used much like ambrosia.
• The Cowplant returns in this game, and unlike in the previous games, can be grown from a seed. Its elixir, gained from eating Sims, can be used to extend a Sim's lifespan.
• The Book of Life can be used by a Sim to revive another Sim, providing a potential means of immortality as long as there is a Sim to revive the one who dies.
• In The Sims 4: Get to Work, Sims in the science career can create an Age-Away serum after a scientific breakthrough that can be used like the Potion of Youth.
• In The Sims 4: Seasons, at level 10 flower arranging it is possible to scent an excellent quality arrangement with orchids. A Sim may then inhale its life essence, increasing their lifespan by one every 24 hours. It is thus possible to stay immortal with a reliable supply of orchids.
• In The Sims 4: StrangerVille, once a Sim has progressed far enough in the StrangerVille story line, they will reach the deepest part of the Secret Lab and encounter the Mother Plant. Attempting to communicate and build a relationship with it will eventually allow the Sim to request a gift once a day, one of these being life extension, which will reset the Sim to the beginning of their life stage. This can be used to prolong a Sim's life indefinitely.
• With The Sims 4: Vampires, sims can turn into a vampire, whom are all immortal. 
• In The Sims 4: Realm of Magic, if the sim is a spellcaster, a potion of rejuvenation or immortality can be brewed, then have the sim drink it to prevent dying of old age.
• In The Sims 4: Werewolves, if the sim is a werewolf, a werewolf ability, called “Immortal Wolf”, allows the werewolf to become immortal. This prevents dying of old age, but it won’t stop a sim from aging up.

Trivia

• Some service NPCs, such as firefighters, cannot be killed unless added to the household through console commands.
• The Grim Reaper is believed to be immortal, although it is difficult to tell as a new Grim Reaper could be generated by the game if the first one dies. In Sims 4 the Grim Reaper possesses the trait trait_isGrimReaper that renders the sim immune to death.
• Despite being undead, Bonehilda is not immortal and can be killed.