Originating as a monk from Orin Temple, Krillin trained there since age four but endured bullying as the weakest student. Seeking greater strength, he journeyed to Master Roshi's island at thirteen, initially viewing Goku as a rival. His early personality displayed jealousy and selfishness, attempting to undermine Goku during training. This rivalry transformed into lifelong friendship through shared hardships under Roshi's tutelage, establishing Krillin as Goku's closest human ally. Physically, Krillin lacks a visible nose, humorously described as breathing through skin pores. Six dots on his forehead represent moxibustion burns, resembling Shaolin monk markings. He is not naturally bald, shaving his head as part of monastic tradition to "unfetter ki," though he grows black hair post-retirement before occasionally reverting to baldness. His eyes transitioned from white to skin-toned in later series. As a martial artist, Krillin wears variations of the orange Turtle School gi but adopts casual attire or police uniforms during retirement periods. He develops signature techniques: the Kamehameha energy wave, the Solar Flare for temporary blindness, and the Destructo Disc, a razor-sharp energy disk capable of cutting nearly anything. Considered one of Earth's strongest humans, his power stems from rigorous training under Roshi, Kami, and King Kai, augmented by Grand Elder Guru unlocking his latent potential on Namek. Despite frequently being outmatched by non-human foes, his ingenuity in combat and ability to sense hidden powers remain assets. Key battles define his journey: killed by Tambourine during King Piccolo's reign and revived via Dragon Balls; instrumental against Saiyan invaders, helping defeat Nappa and sparing Vegeta per Goku's request; traveling to Namek where Frieza's murder triggers Goku's first Super Saiyan transformation; sparing Android 18 despite having her deactivation remote, leading to their marriage; killed again by Super Buu while aiding allies' escape. Post-conflicts, he retires to family life with Android 18 and daughter Marron but returns for critical threats like Frieza's resurrection and the Tournament of Power. There, he confronts illusions of past killers (Tambourine, Frieza, Buu) to overcome trauma before competing. Krillin's personality evolves from early pettiness to unwavering loyalty and moral grounding. He provides comic relief through reactions to absurd situations and self-deprecating humor about his stature or misfortunes. His relationship with Android 18 begins when he destroys her shutdown device, captivated by her humanity. As a husband and father, he prioritizes family stability while remaining willing to fight for Earth's safety. Professional shifts include teaching martial arts and later working as a police officer. His narrative significance includes being the most killed character, symbolizing human vulnerability amid god-like allies. His friendship with Goku spans Goku's growth from orphan to multiversal protector, offering perspective on consequences often overlooked by Saiyan warriors.