Raditz is a full-blooded Saiyan warrior and a central antagonist in the opening arc of Dragon Ball Z Kai, the re-edited version of the original Dragon Ball Z anime. He is the biological older brother of Goku and the first-born son of the Saiyan warrior Bardock and his wife Gine. Born on Planet Vegeta, he became a soldier in the Frieza Force alongside Vegeta and Nappa, spending his life traveling to weaker planets and conquering their inhabitants. Because he was away on a mission when Frieza destroyed Planet Vegeta, Raditz was one of the very few full-blooded Saiyans to survive the extinction of his race. He is also known by the nickname Raditz the Runt, and he is described as a mid-class Saiyan warrior.

In terms of background, Raditz was raised with a traditional Saiyan upbringing on the battlefield, which shaped him into a harsh, brutal, and arrogant fighter. That upbringing stands in sharp contrast to Goku, who was sent to Earth as an infant and, after a childhood injury erased his Saiyan instincts, grew up as a kind-hearted hero. Raditz embodied the darker side of Saiyan culture: a belief in strength, conquest, and dominance over empathy or compassion. He was cold and cruel in his methods, treating weaker beings with contempt and showing no hesitation to threaten or harm innocents. His arrogance was also his defining flaw, as he relied on his natural brute strength rather than developing strategic thinking or battle intelligence, which ultimately contributed to his downfall.

Raditz's primary motivation was to recruit Goku into the Frieza Force, believing his missing brother would naturally join the Saiyan cause. He traveled to Earth for that purpose and, upon finding Goku, revealed the truth of his heritage: that Goku was originally named Kakarot and had been sent to Earth as a baby to conquer the planet. When Goku refused to abandon his family and his life on Earth, Raditz turned hostile and kidnapped Goku's young son Gohan, using the child as a hostage to force Goku into cooperation. This act demonstrated his cold and calculating nature, treating even his own nephew as a tool rather than family.

Raditz's role in the story is brief but enormously significant. He is the first major villain encountered in Dragon Ball Z Kai, and his arrival shatters the peaceful era that followed Goku's previous victories. His presence forced two former enemies, Goku and Piccolo, to form a temporary alliance against a common threat. The battle with Raditz also introduced concepts that would define the rest of the series, including Scouters, devices used to measure an opponent's power level, and the existence of the Saiyan race as a larger cosmic threat. During the fight, Gohan, witnessing his father's suffering, unleashed a hidden burst of power that stunned Raditz and foreshadowed the boy's immense potential. In the end, Goku sacrificed his own life by holding Raditz in place so Piccolo could strike them both with his Special Beam Cannon technique. Dying shortly after, Raditz used his Scouter to transmit information about the Earth and its Dragon Balls to Vegeta and Nappa, who then set their sights on the planet, directly setting the stage for the next major conflict.

Raditz's key relationships are defined by duty and blood rather than affection. With Goku, he shared only a biological bond, and he viewed his brother with disdain once Goku rejected his Saiyan heritage; their relationship highlights the contrast between Saiyan aggression and the values Goku developed on Earth. With Gohan, his nephew, he saw only leverage, taking him hostage without hesitation. With Piccolo, he was an enemy who briefly drew the Demon King into an uneasy alliance with Goku. With Vegeta and Nappa, he was a subordinate and comrade within the Frieza Force, and his final message to them became the spark for their invasion of Earth. His parents, Bardock and Gine, are part of his backstory, but their values differed noticeably from his own, as Raditz fully embraced the warrior mentality that defined most Saiyans.

Raditz does not undergo meaningful development over the course of the story, as his appearances are limited to a short arc that ends in his death. He remains consistently arrogant and dismissive of his opponents, underestimating Goku, Piccolo, and even young Gohan until the very end. His significance lies not in his own growth but in how his arrival changes the lives of the main characters: Goku learns the truth about his origins, Gohan begins the journey toward becoming a fighter, and the heroes of Earth are introduced to threats from beyond their planet.

In terms of abilities, Raditz was far more powerful than any warrior on Earth at the time of his arrival, with a power level that dwarfed both Goku and Piccolo. He possessed the standard Saiyan physical traits of superhuman strength, speed, endurance, and the ability to fly and project energy blasts. His signature technique was Double Sunday, a quick twin beam attack fired from his palms that was powerful enough to sever Piccolo's arm. He also demonstrated a counterattack ability that allowed him to strike opponents from behind. His Scouter gave him the tactical advantage of measuring enemy power levels and transmitting communication across space. Like all Saiyans with a tail, Raditz could potentially transform into a Great Ape under the light of a full moon, a transformation that multiplies a Saiyan's power roughly tenfold, though this form was never shown in his brief appearance. His tail, however, also carried the traditional Saiyan weakness, as gripping it causes intense pain. Despite his immense power and cruelty, Raditz's overconfidence and inability to adapt when his enemies worked together proved to be the weaknesses that cost him his life.