We first meet Krillin in Dragon Ball. He travels to Kame House in order to request that he train under Master Roshi. Very clever and sneaky, he gives Roshi a gift that he can not resist, magazines with pictures of babes. Roshi agrees to train him if he can bring him back a pretty girl. But Roshi is concerned that the boy will bring back an unsuitable one so he sends both Krillin and Goku on an adventure to bring back the Legendary Sleeping Princess. Krillin keeps his head shaved to show his dedication to the martial arts and probably also to keep his opponents from being able to hold him by his hair. He also has the six scars from burns made on his forehead. Goku and Krillin must team up together to get through their adventures and become good friends. When they return they both continue their training under the Turtle Sage.

After their training is complete both Krillin and Goku compete in the Tenkaichi Budoukai wearing similar gi's. It is during his battle with Piccolo Daiomao that Krillin dies for the first time. Luckily, he is wished back to life with the Dragon Balls.

The next appearance that Krillin makes is during the first Episode of Dragon Ball Z. It seems the fighter has lost touch with his best friend in the past few years because he is surprised when he learns that Goku is married and he has a child. During the upcoming fights with Radditz, Nappa and Vegeta, Krillin again wears his orange gi, but unlike Goku, he wears no shirt under it nor does he wear weighted boots. Instead, he wears small black monk's shoes. Krillin uses his own attacks to fight the evil Saiyans but Krillin is able to help defeat Vegeta by forming and throwing the Spirit Bomb made from the energy that Goku had collected.

Goku having being hurt during the battle with Vegeta, is recovering in the hospital when Bulma, Krillin and Gohan, set out for the Planet Namek to recover the Namekian Dragon Balls. Because Piccolo was killed during the battle, the Earth's Dragon Balls disappeared with Kami and Piccolo. Bulma, Krillin and Gohan, now knowing that Namek also has Dragon Balls, set out to find them so that they can wish back, Yamcha, Tien, Chiatozu and Piccolo. Krillin, wears a baseball cap with his name on it and regular clothing for the trip. Once at their destination, he changes clothes again.

On Planet Namek, Krillin again changes into his orange gi, again without the blue shirt that Goku wears. It is here that we really see a lot of Krillin. His courage and intelligence is brought out when both he and Gohan must face Frieza's forces on their own. Krillin even makes an attempt to stand up to Vegeta, but seeing that he is no match for the saiyan, he gives up his dragon ball to protect Bulma. Later, he faces Guldo with Gohan. The two, although are doing very good in the beginning, are caught in Guldo's special technique of freezing time. Luckily, Vegeta intervenes and the two are saved. The next challenge is Recoome, who turns out to be a very strong opponent. All are injured in the following battle and Krillin is almost killed. Goku finally arrives and is able to rescue and revive the fighters with sensu beans. At this point, Goku faces off with Recoome and Krillin and Gohan are sent to retrieve the dragon balls. Krillin is then easily tricked when Captain Giynu shows up disguised in the stolen body of Goku. Krillin again shows that he is a strong and disciplined opponent when he is able to put aside the appearance of Goku's body and fight Ginyu. He is also able to pull Gohan through the fight.

After Ginyu is returned to his body and then into the body of a frog, Krillin, Gohan and the injured Goku are taken into Frieza's ship by their new ally, Vegeta. Much to their surprise, Vegeta helps Goku to recover and gives Krillin and Gohan Saiyan armor to wear for their upcoming battle with Frieza. Krillin is given a black outfit to wear under the older version of the Saiyan armor. Unfortunately, the armor is useless against the sharp horns of Frieza. The evil alien is able to punch right through the armor and without Dende's quick healing abilities, Krillin would have perished. Unfortunately, Frieza gets rid of him in the end by blowing up the warrior just as the group's guard is down. It is the pleading of Krillin and his death that finally pushes Goku over the edge so that he reaches a new level, Super Saiyan.

After Krillin is wished back with the Namek Dragon Balls, life goes on without the presence of Goku. During this time of peace, Krillin is with his new girlfriend Maron. He wears white slacks and coat with a white hat. The peace of the Earth is again threatened by an old enemy. Gohan and Krillin are left to fight against the evil Garlic Jr. Luckily, they are not effected by Garlic Jr.'s evil mist and are able to defeat the evil menace.

Although the Z fighters think that Frieza had been destroyed, Krillin and the others soon learn that the evil tyrant was not so easily defeated. Frieza returns, but is cut down and destroyed by a mysterious young boy that also has the ability to become a Super Saiyan. The youth warns the group that a new menace awaits them that is even more dangerous than Frieza. The fighters are given three years to prepare to meet the powerful androids that will be created by Dr. Gero. Krillin returns to Master Roshi to continue his training while the others go their separate ways to also continue their preparations. When the androids finally do arrive, Krillin again wears his orange gi, but this time he wears a blue shirt underneath and weighted boots. The fighters learn that the original two androids that appear are not the ones that the Future Trunks is plagued with. Androids 17 and 18 are released along with the huge Android 16. They terrorize the area and fight the Z warriors for the first time, easily defeating them. Krillin does not take part in this battle because he sees that they are no match for them. It is at this point that he is kissed by Android 18 and falls in love with her.

After Cell is destroyed, Krillin, who has taken care and protected Android 18, begs the other fighters to let her live. He then wishes for the bomb to be removed from her so that she will not be a threat to anyone. Eventually the two marry and have a daughter, Marron. Krillin, now a family man, lets his hair grow out again.

Krillin's daughter Marron is now a teen and Krillin has grown a mustache. He now deals with headstrong Android 18 and his emotional daughter. Poor Krillin.

Krillin is later seen still with the mustache but his hair has gotten gray where his wife, being an android has retained her youthful appearance.