Immortality

Immortality (不死, Fushi), also called Eternal Life (永遠の命, Eien no Inochi), is the concept of living in physical or spiritual form for an infinite length of time without dying. There are several outside methods in the series which can be sought after in order to become immortal, the most common being to make such a wish to the Eternal Dragon, Shenron, using the seven Dragon Balls.

Methods of gaining immortality

 * Collecting the seven Dragon Balls (or, alternatively, the Namekian Dragon Balls or Black Star Dragon Balls) and having a wish for immortality granted by an Eternal Dragon. This method also extend immortality even to unnatural taking of life, such as murder or suicide.
 * Drinking the immortality elixir alluded to in the Dragon Ball manga.
 * Having Master Roshi's pet, the Immortal Phoenix, bestow immortality. This method is rendered unavailable some time before the beginning of Dragon Ball, due to the irony that the Immortal Phoenix died from being fed "tainted bird seed".
 * The grueling process of converting a human into a cyborg entails them freedom from a death by natural causes.

Characters who are immortal

 * Master Roshi: When Roshi quips Goku to grant "a dying old man his last wish" (referring to having Bulma allow him to feel her breasts) in exchange for the Bansho Fan, Turtle rebuts that "'This dying old man' drank the immortality elixir." However it should be noted that despite being immortal, Master Roshi has died of unnatural causes on two different occasions, the first being during the King Piccolo Saga when he attempts to sacrifice himself to stop King Piccolo's dominion over Earth, and the second being during the Fusion Saga when he is eaten by Super Buu.
 * Darkness: The mysetrious entity which guards the Ultra Divine Water in the Cave of Darkness. Darkness tells Goku that the two of them could live together forever while fooling him with illusions, suggesting that he is immortal.
 * Garlic Jr.: In the film Dragon Ball Z: Dead Zone, Garlic Jr. is successful in his campaign to wish for eternal life from Shenron. As such, he is abnormally defeated not by being slain but by being victimized by his own ploy, the Dead Zone, wherein he is trapped for several years until his escape in the filler Garlic Jr. Saga of Dragon Ball Z. It should be noted that Garlic Jr. is the only character in the series to have complete and unhindered immortality. Whereas characters such as Master Roshi and the androids are free from death by natural causes but are still susceptible to such acts as murder or suicide, Garlic Jr. seems to be literally incapable of dying.
 * While not completely immortal, it is explained by Dr. Gero shortly after activating Android 17 and Android 18 that the process of configuring humans into cyborgs essentially grants them "eternal life". This only applies to aging and death by natural causes, as while their energy never drains, they are still capable of being killed in battle.
 * Cell states that he will live forever as long as he isn't completely annihilated.

Characters who have pursued immortality

 * Vegeta: The proud Saiyan warrior seeks the Dragon Balls of Earth, where he is encountered and defeated by Goku. After recovering, Vegeta searches Namek for the Dragon Balls of that planet, which he is successful in stealing from Frieza (with the exception of one he locates himself). He loses the artifacts to the Ginyu Force, before coming to gain possession of them once again with the arrival of Goku. He nearly loses the opportunity to become immortal when Krillin, Gohan andDende summon the Eternal Dragon of Namek, Porunga, in his absence, but he realizes with enough time to track the group down and force Dende to make the wish (as Porunga requires his summoner to speak in Namek dialect when making a request). The wish ultimately fails however, when Grand Elder Guru dies, thus killing the Eternal Dragon and crippling Vegeta's conquest for immortality. After being resurrected, he gave up on immortality despite the Earth's Dragon Balls being revived.
 * Gogeta: In his ending in the PSP game Dragon Ball Z: Shin Budokai, Gogeta considers wishing for immortality but eventually decides that a lot of delicious food would be better. It is likely that his wanting for immortality is due to Vegeta's influence inside him, and his wanting for delicious food comes from Goku.
 * Nappa: A Saiyan who travels to Earth with Vegeta to seek out the Dragon Balls. Their plan ultimately fails when Goku arrives and pummels Nappa, who ends up being betrayed and killed by Vegeta.
 * Frieza: The self-proclaimed "Lord of The Universe" seeks the Dragon Balls in an effort to solidify his terrifying influence by gaining true immortality. Frieza becomes increasingly desperate to fulfill this desire as more threats to his campaign begin to surface on Namek, such as Vegeta, the Earthlings Krillin and Gohan, a Namek victim's curious last words that Frieza could never make a wish even with the Dragon Balls gathered, and finally the arrival of Goku. Ultimately, Frieza loses his opportunity to wish for immortality to Vegeta, who in turn also fails to have this request granted when Porunga, the Eternal Dragon of Namek, prematurely dies. After Porunga is revived, Frieza makes a desperate attempt to wish for immortality, but it is rejected due to him not knowing he has to speak the wish in the Namekian language. Dende seizes this opportunity to wish for all living beings on Namek except for Goku and Frieza to be transported to Earth. Frieza does gain immortality in several video game what-if scenarios, such as "The True Ruler" in Dragon Ball Z: Budokai and his story in Dragon Ball Z: Supersonic Warriors. When he gains immortality in the Another Age scenario "Spirit Bomb" in Dragon Ball Z: Battle of Z, Frieza also gains the ability to create non-immortal clones of his forms and becomes completely invulnerable to everything but the Universal Spirit Bomb.
 * Vodka: An Earthling mob leader employing Mercenary Tao during the Cell Games Saga, who desires immortality so that he may escape Cell's path of destruction.
 * Cooler: In Piccolo's scenario in the Nintendo DS game Dragon Ball Z: Supersonic Warriors 2, Cooler and his armored squadron go to New Namek in order to gather the Namekian Dragon Balls so that Cooler can be immortal. They are stopped and defeated by Gohan and Piccolo.
 * Future Babidi: In the PSP game Dragon Ball Z: Shin Budokai - Another Road, Future Babidi planned to have eternal life as one of his wishes with the Namekian Dragon Balls. He is eventually absorbed by Buu and never gets his wishes.

Trivia

 * Daizenshuu 2 states that Majin Buu has an immortal body because he can regenerate it. It is shown however that he can be killed when he is obliterated by Goku's Super Spirit Bomb.
 * While in Hell, Frieza and Cell gain a sort of immortality, coming back everytime they are defeated as they are already dead. Although, this point is countered during the Buu Saga, when Goku states that when fighters that are already dead are killed, they are wiped from existence completely.