There are so many characters in the dragon ball series it would take for ever to name them all, not to meantion there description. So I have narrowed it down to the most crucial and popular characters through out the Z series.
Master Roshi: An ancient and wise master of martial arts, Roshi has
accumulated great power and knowledge. He’s completely bald and has
a long, white beard. His home, the Kame house, continues to serve as a gathering
place for the good guys. Although he may appear strange, frail and harmless,
Master Roshi is indeed a great warrior. He originally trained Goku and
Krillin when they were young boys. The first earthling to ever understand
how to nurture and control the Power of Light, Roshi trains Goku and
Krillin in its use.
King
Kai: King Kai is known throughout the
universe as one of the greatest fighters and martial arts teachers His house is on a tiny planet at the end of Snake Way. His companions include
a goofy monkey named Bubbles and a grasshopper named Gregory. King Kai
possesses a humorous, corny sense of humor (he's always telling jokes
or puns) as well as great wisdom. Fortunately for our friends, he can
communicate telepathically, giving them good advice and warnings in
critical situations. Goku trained under King Kai.
Yamcha, Chiaotzu, Tien, and Piccolo also train under King Kai when they
are sent to the 'Next Dimension.'
Goku:
Goku is the hero of Dragon Ball Z, the most powerful warrior on earth
and the first to become Super Saiyan in over 1000 years. When the Saiyans
arrive, Goku learns the mysterious secret of his own past: He is a Saiyan
formerly named Kakarot. Goku was sent to Earth as a baby to grow up
and destroy the planet, but a head injury as a child scrambled Goku’s
programming. Instead of growing up to become a destructive super-warrior,
he became innocent and pure of heart, fighting for good. Goku is peaceful,
good natured, honest, loving to his family and friends, loyal, trustworthy,
brave. He originally trained under
Master Roshi and wears his symbol until he trains under King Kai. Goku grows up and marries Chi-Chi. Together
they have two sons: Gohan and Goten.
Gohan:
Gohan is Goku and Chi-Chi's eldest
son. He is idealistic, good and pure like his father. Gohan reveals
his tremendous fighting potential when the earth is threatened. His
heritage as part Saiyan and part human, make him stronger than if he
were of one race alone. With Goku's departure to the next dimension
and the eminent arrival of Saiyans stronger than Raditz, Gohan is key
to the survival of Earth. Thus Piccolo, a former enemy of his father,
joins forces with the good guys and trains Gohan for the upcoming battle.
Over time, Gohan becomes friends with Piccolo, looks up to Piccolo and
even wears similar clothing. Although initially a wimp, Gohan's training
in the wilderness and subsequent fighting make him both brave and loyal.
He was the first to reach Super Saiyan level 2
stage.
Goten:
Goten is the second son of Goku and Chi-Chi, and is Gohan’s little brother.
Goten loves to train in martial arts. He quickly develops incredibly
strong powers and is the youngest to go super saiyan, that enables him
to fight alongside the adults in their mission to defend earth. Goten’s
best friend is Trunks who is approximately one year older. They are
often seen together. Goten goofs around when he fights.
Chi-Chi:
As the headstrong wife of Goku, some say Chi-Chi is the most powerful
woman on Earth. They met in Dragon Ball
when Chi-Chi saves Goku. Her father, Ox-King, trained her to be a formidable
fighter in her own right. In Dragon Ball Z, Chi-Chi is mainly seen as
a loving wife and doting mother, concerned and protective, perhaps even
over-protective, of her family.
Krillin:
As a young boy, Krillin studied martial arts with Goku under Master
Roshi. Originally he and Goku were fierce rivals, but now they are best
friends. A short, bald warrior, Krillin provides comic relief in tense
situations as he tries to keep up with Goku and some of the other more
powerful warriors. A good fighter on his own accord, he's always there
to help Goku. He can and has saved his friend's life more than once.
In fact, Krillin unleashes an incredibly powerful energy blast shaped
like a flying disk that can slice through mountaintops. Loyal,
courageous and dedicated to his friends, Krillin is willing to fight
against the Saiyans.
Piccolo:
Goku's onetime archenemy, Piccolo is the second strongest being on the
Earth, born as a concentration of Kami’s negative spirits. He has powerful
energy blasts, can split into two or four separate entities, and has
the ability to regenerate limbs. He is often seen in a white cape. Originally
from the far away planet Namek Piccolo starts off fighting Goku to rule the world. When
the Saiyans arrive he joins forces with Goku. At first it is an uneasy
alliance, but as the story unfolds, their bond becomes stronger. While
training Goku's son Gohan for the upcoming battle against the Saiyans,
Piccolo develops a special bond with Gohan. Through Gohan, the only
person who has ever been a friend to him, Piccolo starts changing character
for the better. He ends up sacrificing his own life to save Gohan. While
battling with Frieza, Piccolo merges with Nail, the last of the Namekain
warriors and former guardian of Guru. From this merging, Piccolo gains
Nail’s ancient Namek fighting style, greatly enhancing Piccolo’s powers
and abilities.
Gotenks:
Goten and Trunks form this new entity by the Metamoru art of Fusion,
which was taught to Goku and is passed on to Goten and Trunks. The fusion must occur between two
beings of equal power and is accomplished by a goofy looking, mirror-image dance.
This type of fusion only lasts 30 minutes, and they must recuperate
for one hour before fusing again. Goten and Trunks are first trained
in the art of Fusion by Goku and then by Piccolo. They try several times
before getting it right, creating two awkwardly formed Gotenks in the
beginning. Once perfected, the fused Gotenks is an incredibly powerful
fighter. Like Goten and Trunks, Gotenks has an amazing ability to learn
moves quickly, and quickly manages to go to Super Saiyan and even Super
Saiyan 3
Videl:
Seventeen years old, Videl is an expert at martial arts and is the daughter
of Hercule, the Martial Arts Champion of the World. Videl attends Orange
Star High School with Gohan. She is often called upon by the city to
aid in police matters. She is determined to unmask the Great Saiyaman.
He also teaches her to fly. Eventually Videl marries Gohan and they have a daughter, Pan.
Bulma:
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 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. 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.
Tien:
Tien is a three-eyed man intent on training to be strong. Originally
trained by one of Master Roshi's rivals, Tien switched sides and became
a Z fighter. He beat Goku at a worldwide martial arts tournament, he is
able to stop a waterfall with a blast and can crush rocks on his head.
His fighting techniques include the ability to hover in the air, throw
concentration bombs, blind with flashes of light, and split into two
or four separate entities. Tien can communicate telepathically
with Chiaotzu, his best friend.
Yamcha:
Yamcha is a longtime friend and ally of Goku's, though he was once a
notorious bandit. He is sometimes accompanied by Paur, his devoted cat
companion. He is anxious and willing to be trained by Kami and to join
the upcoming battle against the Saiyans even though he understands that
the odds will be against them. In the heat of battle Yamcha volunteers
to fight the Saibamen instead of Krillin because Krillin has already
been brought back to life by the Dragon Balls.
Trunks:
Trunks is the son of Bulma, a headstrong technical genius, and Vegeta,
one of the most powerful fighters in the Dragon Ball Z universe. He first appears in Dragon Ball Z in his
mid to late teens. He is from the future and has witnessed a threat
to Earth which cannot be stopped in that time. He has come back in time
to try to save the Earth of his time. Trunks returns to our
timeline again in the Android Saga to ensure that the androids do arrive
on Earth. He is also born during this saga, so we have the opportunity
to see him both as a teenager and a baby at the same time. He continues
to exist as a boy and a teen until the end of the Cell Saga, when the
older Trunks returns to his original timeline.
Chiaotzu:
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.
Vegeta:
Vegeta is a powerful Saiyan. He is a 'Super Elitist' and a prince, the
son of King Vegeta, past ruler of the Saiyans. Vegeta and his comrade
Nappa are two of the last surviving Saiyans. They come to Earth to destroy
all life and sell the planet. Though physically smaller than Goku, Vegeta
can power up to unbelievable levels destroying entire planets. He is
a fierce rival of Goku's, striving always to seek power levels as high
or higher than Goku and to reach Super Saiyan level. Ambitious and determined,
Vegeta wants the Dragon Balls to gain immortality. He is determined
to destroy Frieza. After the Namek Saga he fights on the side of the
good guys and becomes the father of Trunks.
Dende:
The lone survivor from his village on the Planet Namek, Dende was rescued
by Krillin and Gohan. Unlike Piccolo and other Namekian warriors, Dende
does not possess strong fighting abilities. But he does have another
crucial capability: the power to heal. Dende is thus important to the
good guys during the battle with Frieza. Trustworthy and caring, Dende
is loyal to Guru and his fellow Namekians. Later in Dragon Ball Z, Dende
replaces Kami as the guardian of the Earth.
Kami:
Kami, guardian of Earth is originally from the Planet Namek. He created
the Dragon Balls on Earth. Desiring to be good and pure, Kami cast off
his negative evil side which became Piccolo. Thus the two are mysteriously
linked. If and when one passes away, the other will pass away also.
And of course, if Kami the creator of Earth's Dragon Balls passes away,
so will the power of Earth's Dragon Balls. He has some capability of
seeing into the future, and can also sense the change when Piccolo starts
becoming a better person. Kami brings Tien, Yamcha, Chiaotzu, and Krillin
together for training in the famous Pendulum Room, the center of all
past, present and future, and then sends them back to earth to prepare
for the Saiyans. Later, Kami fuses with Piccolo to make Piccolo stronger.
Hercule:
An expert at PR, Hercule has always been a champion at gaining credit
for himself. He is not always the tough guy he appears to be, in fact
he can be quite cowardly. He was the World Martial Art’s Champion of
the previous tournament and manages to win the title again by doing
a side deal with Number 18, the other finalist for the championship
title. Despite his faults, he does the Earth a good turn. He befriends
Majin Buu eventually convincing Majin Buu to stop hurting the people
of Earth. Unfortunately, this pledge does not last when Majin Buu becomes
angry because his puppy is hurt.
Main
Dragon ball Z
Master Roshi: An ancient and wise master of martial arts, Roshi has
accumulated great power and knowledge. He’s completely bald and has
a long, white beard. His home, the Kame house, continues to serve as a gathering
place for the good guys. Although he may appear strange, frail and harmless,
Master Roshi is indeed a great warrior. He originally trained Goku and
Krillin when they were young boys. The first earthling to ever understand
how to nurture and control the Power of Light, Roshi trains Goku and
Krillin in its use.
King
Kai: King Kai is known throughout the
universe as one of the greatest fighters and martial arts teachers His house is on a tiny planet at the end of Snake Way. His companions include
a goofy monkey named Bubbles and a grasshopper named Gregory. King Kai
possesses a humorous, corny sense of humor (he's always telling jokes
or puns) as well as great wisdom. Fortunately for our friends, he can
communicate telepathically, giving them good advice and warnings in
critical situations. Goku trained under King Kai.
Yamcha, Chiaotzu, Tien, and Piccolo also train under King Kai when they
are sent to the 'Next Dimension.'
Goku:
Goku is the hero of Dragon Ball Z, the most powerful warrior on earth
and the first to become Super Saiyan in over 1000 years. When the Saiyans
arrive, Goku learns the mysterious secret of his own past: He is a Saiyan
formerly named Kakarot. Goku was sent to Earth as a baby to grow up
and destroy the planet, but a head injury as a child scrambled Goku’s
programming. Instead of growing up to become a destructive super-warrior,
he became innocent and pure of heart, fighting for good. Goku is peaceful,
good natured, honest, loving to his family and friends, loyal, trustworthy,
brave. He originally trained under
Master Roshi and wears his symbol until he trains under King Kai. Goku grows up and marries Chi-Chi. Together
they have two sons: Gohan and Goten.
Gohan:
Gohan is Goku and Chi-Chi's eldest
son. He is idealistic, good and pure like his father. Gohan reveals
his tremendous fighting potential when the earth is threatened. His
heritage as part Saiyan and part human, make him stronger than if he
were of one race alone. With Goku's departure to the next dimension
and the eminent arrival of Saiyans stronger than Raditz, Gohan is key
to the survival of Earth. Thus Piccolo, a former enemy of his father,
joins forces with the good guys and trains Gohan for the upcoming battle.
Over time, Gohan becomes friends with Piccolo, looks up to Piccolo and
even wears similar clothing. Although initially a wimp, Gohan's training
in the wilderness and subsequent fighting make him both brave and loyal.
He was the first to reach Super Saiyan level 2
stage. 
Goten:
Goten is the second son of Goku and Chi-Chi, and is Gohan’s little brother.
Goten loves to train in martial arts. He quickly develops incredibly
strong powers and is the youngest to go super saiyan, that enables him
to fight alongside the adults in their mission to defend earth. Goten’s
best friend is Trunks who is approximately one year older. They are
often seen together. Goten goofs around when he fights.
Chi-Chi:
As the headstrong wife of Goku, some say Chi-Chi is the most powerful
woman on Earth. They met in Dragon Ball
when Chi-Chi saves Goku. Her father, Ox-King, trained her to be a formidable
fighter in her own right. In Dragon Ball Z, Chi-Chi is mainly seen as
a loving wife and doting mother, concerned and protective, perhaps even
over-protective, of her family.
Krillin:
As a young boy, Krillin studied martial arts with Goku under Master
Roshi. Originally he and Goku were fierce rivals, but now they are best
friends. A short, bald warrior, Krillin provides comic relief in tense
situations as he tries to keep up with Goku and some of the other more
powerful warriors. A good fighter on his own accord, he's always there
to help Goku. He can and has saved his friend's life more than once.
In fact, Krillin unleashes an incredibly powerful energy blast shaped
like a flying disk that can slice through mountaintops. Loyal,
courageous and dedicated to his friends, Krillin is willing to fight
against the Saiyans.
Piccolo:
Goku's onetime archenemy, Piccolo is the second strongest being on the
Earth, born as a concentration of Kami’s negative spirits. He has powerful
energy blasts, can split into two or four separate entities, and has
the ability to regenerate limbs. He is often seen in a white cape. Originally
from the far away planet Namek Piccolo starts off fighting Goku to rule the world. When
the Saiyans arrive he joins forces with Goku. At first it is an uneasy
alliance, but as the story unfolds, their bond becomes stronger. While
training Goku's son Gohan for the upcoming battle against the Saiyans,
Piccolo develops a special bond with Gohan. Through Gohan, the only
person who has ever been a friend to him, Piccolo starts changing character
for the better. He ends up sacrificing his own life to save Gohan. While
battling with Frieza, Piccolo merges with Nail, the last of the Namekain
warriors and former guardian of Guru. From this merging, Piccolo gains
Nail’s ancient Namek fighting style, greatly enhancing Piccolo’s powers
and abilities.
Gotenks:
Goten and Trunks form this new entity by the Metamoru art of Fusion,
which was taught to Goku and is passed on to Goten and Trunks. The fusion must occur between two
beings of equal power and is accomplished by a goofy looking, mirror-image dance.
This type of fusion only lasts 30 minutes, and they must recuperate
for one hour before fusing again. Goten and Trunks are first trained
in the art of Fusion by Goku and then by Piccolo. They try several times
before getting it right, creating two awkwardly formed Gotenks in the
beginning. Once perfected, the fused Gotenks is an incredibly powerful
fighter. Like Goten and Trunks, Gotenks has an amazing ability to learn
moves quickly, and quickly manages to go to Super Saiyan and even Super
Saiyan 3
Videl:
Seventeen years old, Videl is an expert at martial arts and is the daughter
of Hercule, the Martial Arts Champion of the World. Videl attends Orange
Star High School with Gohan. She is often called upon by the city to
aid in police matters. She is determined to unmask the Great Saiyaman.
He also teaches her to fly. Eventually Videl marries Gohan and they have a daughter, Pan.
Bulma:
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 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. 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. 
Tien:
Tien is a three-eyed man intent on training to be strong. Originally
trained by one of Master Roshi's rivals, Tien switched sides and became
a Z fighter. He beat Goku at a worldwide martial arts tournament, he is
able to stop a waterfall with a blast and can crush rocks on his head.
His fighting techniques include the ability to hover in the air, throw
concentration bombs, blind with flashes of light, and split into two
or four separate entities. Tien can communicate telepathically
with Chiaotzu, his best friend.
Yamcha:
Yamcha is a longtime friend and ally of Goku's, though he was once a
notorious bandit. He is sometimes accompanied by Paur, his devoted cat
companion. He is anxious and willing to be trained by Kami and to join
the upcoming battle against the Saiyans even though he understands that
the odds will be against them. In the heat of battle Yamcha volunteers
to fight the Saibamen instead of Krillin because Krillin has already
been brought back to life by the Dragon Balls.
Trunks:
Trunks is the son of Bulma, a headstrong technical genius, and Vegeta,
one of the most powerful fighters in the Dragon Ball Z universe. He first appears in Dragon Ball Z in his
mid to late teens. He is from the future and has witnessed a threat
to Earth which cannot be stopped in that time. He has come back in time
to try to save the Earth of his time. Trunks returns to our
timeline again in the Android Saga to ensure that the androids do arrive
on Earth. He is also born during this saga, so we have the opportunity
to see him both as a teenager and a baby at the same time. He continues
to exist as a boy and a teen until the end of the Cell Saga, when the
older Trunks returns to his original timeline. 
Chiaotzu:
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. 
Vegeta:
Vegeta is a powerful Saiyan. He is a 'Super Elitist' and a prince, the
son of King Vegeta, past ruler of the Saiyans. Vegeta and his comrade
Nappa are two of the last surviving Saiyans. They come to Earth to destroy
all life and sell the planet. Though physically smaller than Goku, Vegeta
can power up to unbelievable levels destroying entire planets. He is
a fierce rival of Goku's, striving always to seek power levels as high
or higher than Goku and to reach Super Saiyan level. Ambitious and determined,
Vegeta wants the Dragon Balls to gain immortality. He is determined
to destroy Frieza. After the Namek Saga he fights on the side of the
good guys and becomes the father of Trunks. 
Dende:
The lone survivor from his village on the Planet Namek, Dende was rescued
by Krillin and Gohan. Unlike Piccolo and other Namekian warriors, Dende
does not possess strong fighting abilities. But he does have another
crucial capability: the power to heal. Dende is thus important to the
good guys during the battle with Frieza. Trustworthy and caring, Dende
is loyal to Guru and his fellow Namekians. Later in Dragon Ball Z, Dende
replaces Kami as the guardian of the Earth. 
Kami:
Kami, guardian of Earth is originally from the Planet Namek. He created
the Dragon Balls on Earth. Desiring to be good and pure, Kami cast off
his negative evil side which became Piccolo. Thus the two are mysteriously
linked. If and when one passes away, the other will pass away also.
And of course, if Kami the creator of Earth's Dragon Balls passes away,
so will the power of Earth's Dragon Balls. He has some capability of
seeing into the future, and can also sense the change when Piccolo starts
becoming a better person. Kami brings Tien, Yamcha, Chiaotzu, and Krillin
together for training in the famous Pendulum Room, the center of all
past, present and future, and then sends them back to earth to prepare
for the Saiyans. Later, Kami fuses with Piccolo to make Piccolo stronger.
Hercule:
An expert at PR, Hercule has always been a champion at gaining credit
for himself. He is not always the tough guy he appears to be, in fact
he can be quite cowardly. He was the World Martial Art’s Champion of
the previous tournament and manages to win the title again by doing
a side deal with Number 18, the other finalist for the championship
title. Despite his faults, he does the Earth a good turn. He befriends
Majin Buu eventually convincing Majin Buu to stop hurting the people
of Earth. Unfortunately, this pledge does not last when Majin Buu becomes
angry because his puppy is hurt.