Krillin is introduced in Dragon Ball as a rival of the main character, Son Goku. Later in the series, he can also be seen having a close relationship with Goku, as well as his child, Son Gohan. Krillin eventually settles down and marries Android #18 after the Cell Games to have a child named Marron
Toriyama originally created Krillin along with the Tenkaichi Budokai as a method to help add depth to the story, as his publicist Torishima had stated that the series' main protagonist, Son Goku, was too plain.
Krillin's appearance stays relatively the same for the majority of the series. He is first introduced at the age of thirteen, with a shaved head and still dressed in the clothing worn at the monastery at which he had been training. He does not possess a nose, and has six spots of moxibustion burns on his forehead, a reference to the practice of Shaolin monks. After the end of the Cell Games Saga Krillin stops shaving his head, and grows his hair out. His outfit also changes as the series progress. When he first appears in Dragon Ball, he wears the yellow-and-orange garb of a monk. Later, he wears the orange gi uniform that is presented to both himself and Goku by Master Roshi in honor of their first martial arts competition. Occasionally he is seen in casual clothes, but for the most part continues to dress for training or fighting at all times. During the Frieza Saga, he wears Saiyan armor provided by Vegeta, but during the Cell Saga he returns to wearing the orange gi, accompanied by a blue short-sleeved undershirt and boots. Prior to the Great Saiyaman Saga, Krillin opted to settle down with his new family, and allows his black hair to finally grow out. From this point on he is shown wearing a workout outfit consisting of a red short-sleeved shirt and brown drawstring pants. Finally, he is shown in DBGT sporting a moustache, wearing grey pants, shirt and tie with a cardigan in his few appearances. As an exclusive in Broly Second Coming, he is seen in Piccolo's casual attire.