Goku is the main character throughout the entire series. He is a saiyan that was sent to earth in order to destroy all life on earth. Goku's mission to destroy life on earth failed due to loss of memory in an accident when he was young. His saiyan brother Radditz came to earth to check on his progress, finding that Goku had lost all memory of his mission Radditz became enraged. Goku was killed along with his brother in battle against each other. In heaven he trained with the great Kaiohsama (English: King Kai). There he learned the art of Kaiohken and really increased his power level by a lot. He was wished back to life with the dragonballs, when he got back to earth he met up with two other saiyans Vegeta and Nappa. He easily defeated Nappa, who was the weakest of the three. Goku spared Nappa's life, but Vegeta killed Nappa in disgust. Then Goku and Vegeta clashed. Goku defeated Vegeta with the help of Gohan, Krillin and Yajirobe. Later on Goku became a super saiyan and defeated Freeza to become the strongest warrior in the universe.
Gohan is the first son of Goku and Chi-Chi. He is half saiyan, half earthling. Gohan first appears in the first episode of DragonballZ. He showed great power even greater than his fathers as a toddler, but he couldn't control his power. He was trained by Piccollo in order to control his power. Gohan's first real battle was against the two saiyans Vegeta and Nappa. Gohan was scared at first, but when he saw that all of his friends were dying he got angry. He showed great signs of courage when he stepped up to Vegeta to save his father. Gohan's next journey was to the planet Namek, he was no match for the foes there such as Freeza, but he did his part and gained tons of power and experience from his encounters with the Ginyu Force and Freeza. Later on Gohan became super saiyan and then he became super saiyan 2 before any of the other saiyans, he was more powerful than even his father at that time. During this stage Gohan defeated Cell with the help of his Goku. Although Gohan didn't manage to remain stonger than his father for long, he was still one of the most powerful and played a major part.
In the alternate timeline, all of the Z team members were killed because of two destructive androids, except for Goku who never gets to fight because of a heart infection. The only survivors were Son Gohan and Trunks. Trunks is the son of Vegita and Bulma. Gohan trained him to become stronger and to reach the level of Super Saiyan. One day the androids appeared and, Gohan confident that he can beat them, had had enough of the destruction. Protecting the inexperienced Trunks, Gohan knocked him unconscious and fought them alone. Gohan was powerful, but was killed nevertheless. Trunks grieved deeply and vowed to one day avenge Gohan's death. Meanwhile, Bulma built a time machine for Trunks so he could go back in the past to find Son Goku. She believed that if he were alive, things would have been different. Trunks came to the past twenty years from the future in a effort to change history. Much like his father, he is hard and aggressive. But unlike his father, he is very polite and has values. He thinks in conventional ways and is very civilized when making decisions. While Trunks was young, he grew up in awe of the father he never knew. Trunks was always anxious about meeting his father. He was both impressed and disappointed once they met. During the battle of Cell however, Vegita showed emotion upon seeing the death of his son (that may be subject to debate for all you hard core nuts!!). Vegita then screamed with passion and attacked Cell. The Z team revived him after Cell was defeated. He decided to return to his timeline once the danger was over. Trunks had trained in that time so that his power surpassed the two androids in his time. When he returned to the future, he not only took with him the skills to defeat the androids but also the knowledge of the father he loved so much.
Vegeta was the prince of the saiyans. He first appeared in dragonball Z, he came to earth in search of the dragonballs which he had heard could grant him any wish. He wanted to wish for eternal life. His plans were ruined by Goku, who defeated him. Later on he formed alliance with Goku and helped defend the earth. He was very jealuos of Goku's power, since Goku was stronger than him. He dispised that he wasn't strong enough to be a super saiyan when Goku had already turned super saiyan. Later on he became super saiyan along with Goku and got to other Super Saiyan stages such as Super Saiyan 2 and 3 but he always trailed behind Goku in maximum power. In DragonballGT he had allowed himself to be taken over by an evil creature called Bebe Di who had increased Vegeta's power and made him stronger than Goku. Using this unfair advantage Bebe-Vegeta could easily pummel Goku, but eventually Goku turned super saiyan 4 and defeated him anyway.
Piccollo is one of the best, strongest and coolest characters in DBZ. He is actually two people, Kame and Piccollo. This is because he was split in half, one side being good, and the other being bad. Kame was the good side, and Piccolo was the bad side. Piccolo was Gohan's trainer, and Gohan was his first true friend. In DBZ Piccollo risked his life for Gohan, and he died in the fight against Nappa. After he was wished back to earth, he merged with Kame. Therefore no more known as Piccolo. He became very strong in this form, and he had no anger in him. Anyhow Piccollo is mostly always in the entire series until GT, when he dies to save Planet Earth. Which showed true courage and faith.
Chibi Trunks: Trunks is the first and only son of Vegeta and Bulma. He is half saiyan, half earthling. Trunks first appears in Dragonballz. Vegeta and Bulma do... you know what, and Trunks is born. Trunks is an extremely powerful child for his age, he along with his best friend Goten have achieved Super Saiyan power at the age of 6 years old. He always seems to get in trouble as a little boy and drags Goten along with him. Trunks looked up to Gohan as a big brother, since he didn't have one.
Son Goten is Son Gokou's second child. Unlike Gohan, Chi Chi does not force him to do as well academically. But he too is powerful, because at the early age of 7, Goten is able to naturally become a Super Saiyajin while training with Chi Chi. The only disadvantage that Goten has is that he is never able to improve upon his power and show his full potential, therefore he never has the ability to surpass Super Saiyajin level 1. Not much changes as he grows older.
Gogeta is the fused state of Goku and Vegeta he makes two appearences in movie 12 and in GT where he is SSJ4. He is exstreamly power ful but not as powerful as Veggeto in DBZ. He looks more like Son Goku than Vegeta and has dull voices of Vegeta and Goku, like all fused warriors.
Gotenks is the fused state of Goten and Chibi Trunks. He is the second and last after goku to go SSJ3. His attacks are Super Ghost Kamikazi and Shine Shine Missile. He is very strong and almost defeated Buu but the fusion wore off due to that he was in ssj3 form.
Vegetto is the fused form of Vegeta and Goku by the potora earings. He is stronger than Gogeta by a bit and is thought to be the strongest warrior in DBZ. The origanl plan was for Goku and Gohan to fuse with the earings but gohan got absorbed by Buu so Goku and Vegeta fused.
Krillin is one of the most popular characters in the DragonBall series and a Buddhist monk by choice. He was Goku's training partner when they were young as they trained with Master Roshi, the Turtle Master. Although considered by many as the most powerful human, the gap between Goku and him stretched and Goku surpassed him. He is also Goku's best friend. Krillin is also one of Gohan's buddies, especially during the Freeza saga. Krillin is almost always in the series. He rarely ever dies. Krillin does have some downfalls though. Like one is that he is bald. Well to fix that he got all seven dragonballs and asked the eternal dragon for hair. Krillin's wife is Android 18 after Krillin uses the dragonballs to make human. They had one child, Marron. Krillin is very pure in heart and sometimes acts funny.
Videl is the daughter of Mr. Satan she is a very good fighter for a human and is the first to figure out that gohan is Great Sayiaman and tells him to teach her how to fly and to enter the tournament or she will tell everyone his secret. She and Gohan eventually get married and have a daughter named Pan.
Pan is Gohan and Videls first and only child. She is quarter saiyan and 3/4 human. Pan he is a teenager in the begginning of DragonballGT. She does not have powers as a regular saiyan since she is only 1/4 saiyan and she is the first and only female saiyan. Pan sneaks aboard the departing ship to help Goku and Trunks to find the dark star dragonballs in DragonballGT. She is an excellent fighter and much stronger than an average girl, but doesn't get too powerful and definitely doesn't turn super saiyan. She is mainly an annoying little girl with a rude attitude and always wants her own way.
Android 17's twin sister, Android 18 has identical fighting strength. Like her brother, she is also created from a human base. During her escape from Cell, Kuririn falls in love with her. To Android 18's surprise, Kuririn wishes for the bomb inside her to be removed with the Dragon Balls. They eventually marry and have a daughter named Marron.
Yamcha is first introduced as a desert bandit that robs people as they pass through his wasteland abode. When he comes upon Goku and friends, he finds out about the Dragonballs and tags along so he can make a wish; he gets very nervous around girls. However, he gets used to Bulma on their journeys, and loses his fear of women. He and Bulma are together for most of Dragonball and half of DBZ. Yamcha does not train much after the encounter with the Saiyajins, yet remains a capable fighter.
Tenshinhan- also known as Tien, is an Earthling warrior. He is about Goku's height and pretty muscular. Tien also has three eyes, two normal eyes, and then one stranger looking eye on the top of his head. Tien is good friends with Chao-Zu, he is also his bodyguard. Tien is the developer of the technique known as the Solar Flare (a fantasically bright light that is formed by fanning one's hands across their face). He is about equal strength with Yamcha, but Krillin is still stronger than him
A master of telepathy, Chiaotzu has the power to stop people in their tracks and to communicate telepathically. This white-skinned, red-checked little being is the devoted companion of Tien. A strong fighter in the early days, Chiaotzu does not hesitate to throw himself onto Nappa's back and self-destruct in an attempt to save his friends. However, his power level does not increase as dramatically as the other Z fighters. Thus, Chiaotzu is not a major warrior in the later episodes of Dragon Ball Z.
Dende is a Little namekian form namek. Dende becomes ruler of earth after kame and piccolo becomes one. He is not much of a fighter but has the power to heal people he creates the new dragon balls on earth.
In Dragon Ball, Bulma was a mixed up teenager with blue hair and a personality quirk that wouldn't allow her to shut up for a second. Now, she's blossomed into a mixed up woman with that same personality quirk. But, Bulma is very important to the team. She is a mechanical genius who can operate and fix anything. She is the one that discovers the capabilities of the Saiyan Scouter and enhances it for their own use. She also takes the lead in finding a spaceship capable of flying to Namek. Bulma designed the Dragon Radar, which tracks the locations of the Dragon Balls. Bulma is also fashion conscious and changes clothing and hairstyles during the series. She often wears clothing with either her name or "Capsule Corporation" on the item. Bulma has known Goku since he was a young boy. In the original Dragon Ball, Bulma had a crush on Yamcha. Although their romance blossoms, it was not permanent. In Dragon Ball Z she outgrows these impulses and settles her affections on Vegeta . They have a son, appropriately named Trunks. The original name for Bulma stands for bloomers (or girl's underwear). Her father is Dr. Brief, of the famous Capsule Corporation