From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Z Warriors (Z 戦士, Z Senshi; FUNimation "Z-Fighters") are a small group of super warriors on Planet Earth. Their duty is to defend the planet from major threats and to protect the seven mystical Dragon Balls from the clutches of evil. The Z Warriors are not officially organized in any way because it is simply a group of fighters who all share the same interest of protecting their home. They all stand together whenever possible to fight off enemies. Son Goku is the co-founder and de facto leader of the group due to his incredible success rate against villains, victory over the evil Saiyans, and his triumph over Freeza. (Kuririn mentions in "Upgrade to Super Saiyan" that Goku is in command.)
During the Dragon Ball anime, a similar team existed, but it was called the Dragon Ball Gang. Their original purpose for coming together was not to protect the Dragon Balls, but to use them themselves. Later, however, the members of the Turtle Hermit School trained by Muten Roshi would join together to combat evils such as Pilaf, the Red Ribbon Army, and King Piccolo, thus this team could be considered an early rendition of the Z Warriors. Its main members consisted of Son Goku, Kuririn, Yamucha, Tenshinhan, Chaozu, Yajirobe, and their supporters.
The first actual formation of the Z Warriors was out of necessity, brought on when Goku was faced with Raditz, who had kidnapped his young son Gohan, who wanted to destroy Earth. Goku formed an alliance with his archrival Piccolo in order to fight for a common cause. The alliance made from necessity is considered the true birth of the Z Warriors.
The term itself is very rarely actually used in the series by anyone other than the narrator. The first being in the Androids Saga when Future Trunks explains to Goku that in the future, "the Earth's Special Forces are gone." The second character to use the term was Gohan when he was training in the Hyperbolic Time Chamber in order to fight Cell. While sleeping, he had a dream in which his mother Chichi said that she did not want Gohan to be in Goku's little gang. Gohan then responds that he is not in a little gang, he is in the Z Warriors.
 Formation and conflicts
The battles against the evil Saiyans, Vegeta and Nappa, was commonly considered the first time the Z Warriors engaged enemies together. During the conflict on Namek some months later, the Z Warriors would ally with the Namekian race against Freeza and his World Trade Organization. This part of the series would be a crucial moment for the forces as they now would gain the support of their once enemy, Vegeta, and Piccolo had finally changed completely for the good. This is also the first time in the series in which a character actually refers to the group as the Z Warriors, when Gohan pleads with Chichi to be allowed to go to Namek with Kuririn and Bulma. He informs her that he too is part of the Z Warriors, and had to be there to protect his friends.
It was not until the Androids conflict some four years after the conflict on Namek that the team of the Z Warriors came full circle. Goku returns from space one year after defeating Freeza, while Future Trunks comes from the future to warn everyone about the Androids that have caused apocalyptic mayhem in his time. (See: Androids Saga) After his defeat on Earth and then brief alliance on Namek, Vegeta decides to return and remain on Earth in anticipation for Goku's return in the hopes that he would be ready to challenge his rival once again. However, When Trunks reveals the future, Vegeta decides to stay and train for the upcoming conflict with the androids rather then prepare to battle Goku. Krillin, Tien Shinhan, Chiaotzu, and Yamcha all eventually are wished back to life as well, and they too soon begin training for the fight with the androids. It is evidently around this time that the series refers to the group of warriors as the "Z Fighters". When the androids do arrive, Trunks returns as well, contributing his efforts with the group. With Goku, Gohan, Piccolo, Trunks, Krillin, Tien Shinhan, Chiaotzu, Yamcha and Vegeta, the group fully forms and it is shown through the opening sequence at this time in the series (the final image is of the aforementioned fighters and Goku as he transforms into a Super Saiyan).
It is also worth noting that while this version of the Z Warriors is a prominent one during the series history, it is the only period of time in which the team consists of these certain members. The Android/Cell Saga was a turning point in the series for a number of reasons, one of them being that the roster of fighters was completely changed after the Cell Games. By the end of the Cell Games, Goku is dead and Gohan has become Earth's primary defender. Trunks returns to his timeline more powerful than ever, thanks to his training in the Hyperbolic Time Chamber with Vegeta, and proceeds to finally destroy the evil versions of Androids #17 and #18 in his world, as well as his timeline's Cell a while later.
Meanwhile, Tien Shinhan bids farewell to the Z Warriors and plans to live in seclusion with his best friend Chiaotzu, realizing he can no longer compete with the powers of the Super Saiyan's. Yamcha retires from fighting for the same reasons as Tien, and never trains seriously again. Krillin continues to live with Muten Roshi, and after a few years, eventually reunites with and later marries Android 18. They soon have a daughter named Marron, and thus Krillin stops training as well. Piccolo decides to live with Dende and Mr. Popo on Kami's Lookout, partly because there is no longer a reason to train, partly because his pupil Gohan has finally surpassed him, and partly because part of him is still Kami and wishes to continue to reside over the Earth. Vegeta however, continues to train hard, hoping to become a Super Saiyan 2 like Gohan, but declares that he will never fight again with his only rival, Goku, dead. Finally, Gohan keeps his promise to his mother Chichi and gives up fighting to study and become a scholar.
 Call to arms once again
By the beginning of the Majin Buu Saga seven years later, the Z Warriors consists of many "next-gen" type of characters. Gohan is eighteen and is the primary hero of Earth, both as a Super Saiyan and his alter ego "Great Saiyaman". The Z Warriors is not really continued, per se, based on the fact that their opponent Majin Buu was so powerful, it mainly called upon one single person to fight him. However, considering the fighters in this time period, it can be said that the "New Z Warriors" consists of the following: Goku, Gohan, Piccolo, Vegeta, Trunks, Goten, Krillin, Videl, and Android 18.
Also worth noting is that unlike the Androids Saga, the Majin Buu Saga is when Vegeta voluntarily became a "good guy". He fought for his family, and to save the Earth, even sacrificing himself in an attempt to kill Majin Buu. He also later came up with the idea of Goku using a Super Spirit Bomb that defeated Kid Buu at the very end. Ten years following Buu's defeat, Goku leaves to train the monster's reincarnate, a young boy named Uub, whom he hopes will become Earth's protector.
 Later years
During Dragon Ball GT, the main fighters for the most part tend to be Goku, Trunks and Gohan's daughter, Pan. Uub does fight in the first major arc, the Baby Saga. However, the Z Warriors (or GT Fighters) do come together in the Super 17 Saga. While Goku's trapped in Hell, Android 17 kills Krillin. This forces the hand of the last major, briefly retired fighters from the end of Dragon Ball Z. The following are the fighters who fought against Super 17: Vegeta, Trunks, Goten, Gohan, and Uub. When the Shadow Dragons appear, Goku defeats the majority, only to finally be outmatched by Syn Shenron, who later becomes "Omega" Shenron. Vegeta arrives and with Bulma's help transforms into a Super Saiyan 4 himself, allowing him and Goku to fuse into Gogeta. Their fusion eventually wears off, and Goku is nearly killed. The final effort of the warrior team is against Omega, in which Vegeta, Gohan, Trunks, and Goten attempt to fight him, despite all failing miserably. Goku eventually returns and kills Omega with a Universal Spirit Bomb. Goku later leaves with Shen Long, thus ending the team forever.
 Dragon Ball Z: The History of Trunks
Main article: Dragon Ball Z: The History of Trunks
In Future Trunks' alternate timeline, Future Son Goku died of a deadly heart virus six months before the arrival of the androids. He could not be wished back, since the Dragon cannot revive anyone who died of natural causes. When the androids did arrive, they proceeded to slaughter Future Piccolo, Future Vegeta, Future Tien Shinhan, Future Yamcha, Future Krillin, Future Chiaotzu, and Future Yajirobe in a horrible battle. Future Gohan somehow managed to survive, only to be killed thirteen years later. The only surviving fighter was Trunks, who traveled back in time in an attempt, not to change history, (as the manipulation of the past would only cause that timeline to take a different path, creating an alternate, separate future), but to see if Goku could help him find a weakness in the Androids; that way, although he could do nothing for those already dead (with Piccolo gone, so were the Dragon Balls), he could still save those who were still alive. After the defeat of Cell, Trunks returned to his own time and was successful In killing both of the androids and Imperfect Cell, thus finally ending the nightmare.
100 years after the Baby Saga, only Pan has survived. The other Z Warriors have died of unknown causes, while two new warriors, Son Goku Jr. and Vegeta Jr., (the great-great grandsons of the original Z Warriors of the same names) now exist.
They are named Chō-senshi (超戦士, Chō-senshi) in Miracle Battle Carddass: Dragon Ball Z Kai.
- Artificial Human No. 18 – Once an android built only for evil, she marries Krillin and changes her ways.
- Chaozu – A human who excels in psychic abilities. He is Tien's best friend and former schoolmate. His last fight on the team is against Nappa, as Tien says that Chaozu "just can't keep up".
- Future Chaozu
- Future Kuririn
- Future Piccolo
- Future Son Gohan – The bleak future version of Gohan who is the sole survivor of the original Z Warriors. He is a Human/Saiyan hybrid.
- Future Son Goku
- Future Tenshinhan
- Future Yajirobe
- Future Yamucha
- Future Vegeta
- Future Trunks Brief – The time-traveling version of Trunks from a devastated future. He is a Human/Saiyan hybrid.
- Kuririn – A Human, he is Goku's best friend and former schoolmate. He has the distinction of being the only Human to stay on the "team" after the Cell Games, as Yamucha, Tenshinhan, and Chaozu all retire. He retires in DBGT.
- Mister Boo – Once an evil magical being, Buu changes his ways (thanks to Hercule) and helps Goku and Vegeta fight his evil counterpart, Kid Boo.
- Oob – A Human reincarnation of Kid Boo, he becomes Goku's pupil at the end of the Dragon Ball Z series.
- Piccolo – A Namekian and once Goku's archrival, he becomes one of his greatest allies. He co-founds the team with Goku.
- Son Gohan – The eldest son of Goku, he is the first Human/Saiyan hybrid.
- Son Goku – A Saiyan and the main character, he is a co-founder of the Z Warriors.
- Son Goten – The second and last son of Goku whose appearance closely resembles that of his father. He is a Human/Saiyan hybrid.
- Son Pan – The granddaughter of Goku and the latest member of the Z Warriors. She helps defeat all the villains who escape from Hell in Dragon Ball GT and gather the Black Star Dragon Balls. One hundred years later, she likely finds the new generation of Z Warriors (Goku Jr., Vegeta Jr.).
- Son Videl – The Human wife of Gohan and daughter of Mr. Satan.
- Tenshinhan – A Human with a third eye who has hit a peak of enlightenment. He is a former assassin and Goku's former rival. He also retires in DBGT, although he continues to train, unlike Krillin and Yamucha.
- Time Patrol Trunks Brief
- Trunks Brief – Vegeta's only son. He is a Human/Saiyan hybrid.
- Yajirobe – A Human samurai who never really wants to help Goku and the rest of the Z Warriors unless there is food involved. He does help the Z Warriors by delivering Senzu from Karin. He also plays a big part in defeating Vegeta by cutting off his tail.
- Yamucha – A Human and once a fearsome desert bandit. Chronologically, he is Goku's first fighting ally. Retires in DBGT.
- Vegeta – The Saiyan Prince and Goku's archrival.
 Fused members
- Gogeta – A warrior made by Goku and Vegeta through a special technique called the Fusion Dance.
- Gokule – Though existing hypothetically only, this warrior is made through a fusion between Goku and Mister Satan when they use the Potara Earrings.
- Gotenks – A warrior made by Goten and Trunks through a special technique called the Fusion Dance.
- Hypothetical Fusion of Goku and Dende
- Majoob – A warrior made by Oob and Mister Boo fusing permanently to fight against Baby.
- Tiencha – Though existing hypothetically only, this warrior is made through a fusion between Tenshinhan and Yamucha after they perform the Fusion Dance.
- Vegetto – A warrior made by Goku and Vegeta when they use the Potara Earrings.
 Allies and supporters
- Artificial Human No. 16 – An android who was originally created to destroy Goku. After his first battle with Cell, he turns to the side of good and offers to fight alongside the Z Warriors at the Cell Games.
- Artificial Human No. 17 – Traitorous android who malfunctioned. Was regarded a failure by Gero. He tries to help Piccolo, 16, and 18 fight against Cell before being absorbed. He maintains a solitary life but eventually helps Goku later so he can summon energy for the Spirit Bomb against Buu.
- Bee – Mr. Satan's and Majin Buu's pet dog.
- Bora – A Native American man who resides in a tepee at the base of Korin Tower.
- Bra Brief – Vegeta and Bulma's daughter and second child. (would be a primary member if she trained)
- Bulma Brief – The human wife of Vegeta and Goku's long time friend, she is a brilliant scientist and is also the daughter of the richest couple in the world.
- Bulma's Mother – Parent of Bulma.
- Dende – A Namekian with healing powers, he becomes Kami's replacement as Earth's Guardian.
- Dr. Brief – Parent of Bulma and president of Capsule Corporation.
- East Kaioshin – An even higher division than King Kai, he is the ruler of the South Galaxy. He eventually fuses with his bodyguard Kibito, creating Kibito Kai.
- Future Bulma Brief
- Future Gyumao
- Future Kame
- Future Kibit
- Future Kibit-Kaioshin
- Future Mister Boo
- Future Old Kaioshin
- Future Pikkon
- Future Pu-erh
- Future Son Chichi
- Future Turtle Hermit
- Gill – A small Machine Mutant that appears in Dragon Ball GT. He accompanies Goku, Pan and Trunks on their quest to locate the Black Star Dragon Balls after consuming the Dragon Radar for energy, and the radar integrates into his software.
- Gure – The wife of Tarble and Vegeta's sister-in-law.
- Gyumao – Chichi's father, who lives on top of Fire Mountain.
- Haiya Dragon
- Kame – The Turtle Hermit's tortoise friend.
- Kame's Son
- Kami – A Namekian, but The Guardian of Earth and creator of the Dragon Balls, his fights are limited to movies and the 23rd Tenkaichi Budokai under the guise of Hero. He ultimately fuses with Piccolo during the Cell Saga.
- Karin – An 800 year old cat that lives below Kami's Lookout at the top of Karin Tower. He supplies the Z Fighters with Senzu Beans whenever he is able to.
- Kibit – Supreme Kai's personal bodyguard. He can heal people and materialize new clothes for them, and eventually fuses with Supreme Kai, creating Kibito Kai.
- Kibit-Kaioshin – The result of the fusion of Supreme Kai and his bodyguard Kibito. He can use an enhanced version of the Instant Transmission ability called the Instantaneous Movement.
- Lunch – The girl with dissociative identity disorder who was Master Roshi's housemaid.
- Marron – Krillin and Android 18's daughter. (would be a member if she trained)
- Mister Boo – Befriended Hercule. Betrayed Babidi and battled his evil incarnation, Evil Boo, as well as aided in the conflict against Kid Boo. Later assimilated with Oob to form Majoob.
- Mister Popo – A genie with eternal life, who is Kami's assistant and also the caretaker and gardener of Kami's Lookout.
- Mister Satan – The champion of the World Martial Arts Tournament and Videl's father. He is made a member after helping complete the Spirit Bomb by telling all the people to give their energy to Goku in order to defeat Kid Buu.
- Nail – A powerful Namekian warrior who serves the Great Elder, he helps the Z-Fighters by delaying Frieza and fusing with Piccolo.
- North Kaio – The king of the North Galaxy, he teaches Goku techniques such as the Kaio-ken and Spirit Bomb.
- Nuova Shen Long – One of the seven Shadow Dragons that appears in Dragon Ball GT, and is the dragon of the Four-Star Dragon Ball. He teams up with Goku and Vegeta in an attempt to defeat Omega Shenron, by surrounding himself and Omega Shenron in a Nova Sphere.
- Pikkon – A deceased warrior of an unknown species from the West Galaxy, he helps Goku and Vegeta by holding off Janemba and helps Goku in the Great Saiyaman saga to stop the villains in Hell.
- Old Kaioshin – An ancient ancestor of the Kaioshin who was trapped inside the Z Sword for eons by a powerful enemy. He performs a ritual that awakens Gohan's full power.
- Olibu – An incredibly powerful famed human from the North Galaxy who has many legends based on him. He, too, is seen taunting Kid Buu in the final episodes.
- Oolong – Goku's shapeshifting pig friend.
- Pu-erh – A shapeshifting cat who is Yamcha's best friend.
- Son Chichi – The human wife of Goku and mother of Gohan and Goten.
- Tarble – The younger brother of Vegeta.
- Tenkaichi Tournament Announcer – The man who hosts every World Martial Arts Tournament, he becomes an acquaintance with the Z Warriors over the years.
- Turtle Hermit – He is Goku's second official mentor (after Grandpa Son Gohan). His fights are limited to films and Dragon Ball.
- Upa – A young boy who lives with his father Bora in the area around Korin's Tower.
- Uranai Baba – The human sister of Muten Roshi and a median between the Other World and Earth.