Cell is one of the "major" villains of DBZ. Others being Vegita, Nappa, Freeza and Buu. All other villains are indeed vile etc. but DBZ is generally divided into sagas named after the largest villain of the period. Cell is no exception. If you were to describe his personality, he has the manners of Freeza and the temper of Vegita, (which makes sense since those are two people he's made up of). The general concept of Cell was brought forth by Dr. Gero, however, Dr. Gero's computer is what really "makes" him. Dr. Gero combined blood samples of Piccolo, Gokou, Vegita, Freeza and King Kold, (which were collected by a robot drone disguised as a bee), and created a small life form which would one day become become Cell. Unfortunately, the amount of work needed to input data into the being and make it intelligent takes a ridiculously long amount of time, so Gero sealed the larva Cell in his secret lab and let his computer tinker away at creating the creature for 24 years. After 24 years, voila! Instant killing machine! However, when Cell emerges as an intelligent being, he's far from being what Dr. Gero dreamed that he would one day become. He basically resembles a walking cockroach. In order to reach perfection, Dr. Gero created two components for Cell to absorb, and once he absorbed the components, he would then become "Perfect" and have no equal in strength.
Those two components were of course, Androids 17 and 18. Now here's the tricky part. The Cell that you all know is NOT from the normal time-line. He comes from a third time-line, and was born in the year 762. In this time-line, Trunks had defeated Androids 17 and 18, unfortunately for Cell, that meant he could not absorb them and become "Perfect".In the year 786, he emerges from Dr. Gero's lab in his first form and begins to absorb the people of Earth to gain power. In the same year, ( after absorbing enough people to increase his power beyond Trunks' ), he siezes�his chance to accomplish his dream. He sneaks up on Trunks, just as he's about to make a departure in his Time Machine to help Gokou and the rest with their fight against the Androids, however, he doesn't get very far. Before he leaves, Cell kills Trunks and steals his Time Machine. In order to fit in the Time Machine, he reverts to an egg state and launches the Time Machine. He ends up in the normal time-line sometime in the year 764. After his arrival, he hatches from his egg and at this point resembles a giant cicada. He crawls several yards away from the Time Machine and burrows down into the Earth to enter his pupa state which he needs to stay in for three years to absorb the neccessary nutrients to reach his first form again. In the year 767 her makes his grand appearance and the Cell Saga begins. Cell is a unique being. Since he is composed of several different species, he has many diverse abilities and fighting techniques. In the anime he can use just about anyone's techniques, but in the manga, he sticks to the techniques that his "genetic parents" could perform. For example, he can regenerate any limb or appendage from any cell in his body. However, his main core is a nerve in his brain. Even if every part of him is destroyed except that nerve, he can still regenerate. He can utilize Kame Hame Ha, and just about any move Gokou can do, the only catch is, he was created from Gokou's cells before he knew certain moves, so Cell needs to see the moves that Gokou learned after his cells were taken in order to perform the specific move, like Shinkan Idou for example. When Gokou's cells were taken, he didn't know the move yet, so Cell wasn't aware that he could perform it, but after he sees Gokou use it, he gains the ability to teleport. He learns it when he self destructs. He does that in hope of blowing up the earth. But Goku teleports along with Cell to King Ki's planet. It blows up the planet along with Goku and King Ki(I bet he was happy). He then regenates and goes back to Earth he is then killed by Gohan with the help of Vegeta on May 26th, 767 AD.
Nappa is Vegeta's rude and obnoxious teammate, who travelled to Earth with him in search of the Dragon Balls, and immortality. Nappa killed most of the special forces, and was eventually killed by Vegeta after failing to defeat Goku when he arrived to save his friends.
I REALLY think hey should have made Piccolo, Krillin, Gohan and company end up killing Nappa, then getting whooped by Vegeta, It would have given The Z Soldiers more credibility and would have made Vegeta more of a bad ass, killing Piccolo.
and, why is Nappa considered a powerful Saiyan when they land? General of the Saiya-Jin army? If he is so strong, how come Bardock, who is TWICE Nappa's strength, is only considered a average fighter?
Radditz is the first villain to appear in the Dragon Ball Z series. He is Goku's older brother, and traveled to Earth to see whether or not his brother Kakarott had conquered the planet. Upon learning of Goku's "reprogramming," Radditz demanded that Goku kill 100 Earthlings and show the bodies to him, or else he would kill Gohan, who was only 4 at the time. Goku and Piccolo chased after him, and after a battle, managed to kill him. However, Goku sacrificed himself by holding Radditz in place so Piccolo could attack, and was killed in the same blow.
Vegeta came to Earth with his ally Nappa to retrieve the Dragon Balls and grant himself immortality. It didn't come as easily as he expected, since he had Earth's special forces to face. He let Nappa handle them, and stepped into the fight once Goku arrived and took care of Nappa. After being defeated, he took off to recuperate, and eventually ran into Krillin and Gohan on Namek, where he was searching for the Namek Dragon Balls. On Namek he allied with the Z fighters to kill Freeza. Vegeta dies on namek. Vegeta eventually learns SSJ. Vegeta ends up having a son (Trunks) and a daughter (Bra).
The tall leader of the Androids and main villain in DBZ Movie 7, The Three Super Saiyan. After 17 killed Dr. Gero his computer worked day and night to form Androids 13-15 and 13 was the last one finished. He was programed with the utter hatred felt by Dr. Gero towards Goku. By himself he's fairly powerful, but when he absorbs two components from Artificial Humans 14 and 15, he turns into Super 13. As Super 13 he is much, much more powerful then all the z fighters at the time. He is much larger in size with blue skin, yellow pupil less eyes and orange Vegeta style hair. Every one who takes a turn at fighting him loses. The only one to really make a difference is Piccolo. Piccolo makes him miss with the attack called the �Super Saiyan Death Bomb� and allows Goku to gather enough energy to make his Spirit Bomb. When Goku was making the Spirit Bomb he went SSJ and absorbed the energy and easily defeated him by puching a hole through his chest.