Gyuumaoh, also known as the Ox-King, is a character from the Dragon Ball series. He is a towering, mountain-like man standing over four meters tall, with a thick beard and a perpetually robust build that shows little sign of aging over the years. His appearance changes notably as the series progresses; he initially appears as a barbaric and fearsome figure wearing goggles and wielding a large axe, but later adopts a more gentle demeanor, dressing in casual, modern clothes and switching to ordinary black-rimmed glasses.

Despite his intimidating nickname, the Demon King, Gyuumaoh is a simple and good-hearted person. In his youth, he was a disciple of the Turtle Hermit, Master Roshi, training alongside Son Gohan, the adoptive grandfather of Son Goku. During this period, he amassed a great fortune in his castle atop Frypan Mountain. However, his greed made him paranoid, leading him to attack anyone who came near, which earned him his fearsome reputation. This behavior changed when the mountain became engulfed in magical flames during a picnic with his young daughter, Chi-Chi. Unable to return home, he was confronted by his old master, who scolded him for his misdeeds. After repenting, Gyuumaoh reformed completely, becoming a fun-loving and harmless man who deeply respects his teacher.

As a father, Gyuumaoh is fiercely protective and caring. His role in the main story is cemented when he asks a young Goku to fetch Master Roshi to extinguish the flames on his mountain, a task that ultimately leads to Goku meeting Chi-Chi and their eventual marriage. From that point onward, he transitions from a former bandit king to a kind and supportive family patriarch. He becomes a devoted grandfather to Gohan and Goten, and a great-grandfather to Pan, often visiting with gifts and helping to keep his hot-tempered daughter, Chi-Chi, calm. His love for his family is demonstrated by his willingness to go to great lengths, such as risking the flames of his own castle to protect Chi-Chi's wedding dress.

While not a central fighter in the series' major conflicts, Gyuumaoh is exceptionally strong by normal human standards. In his prime, he was considered a top-tier martial artist, ranking alongside figures like Master Roshi, Grandpa Gohan, and Mercenary Tao. His body is durable enough to shrug off gunfire and tank shells, and his strength allows him to destroy military vehicles with his bare hands or toss massive boulders into the air. His primary weapon is a massive axe, which he wields with great power. Despite his physical might, he is unable to manipulate ki energy for techniques like flight or energy beams. As the story progresses and enemies become god-like in power, his role as a fighter diminishes. He is last seen in a combat capacity contributing his energy to Goku's Spirit Bomb during the final battle against Majin Buu. Ultimately, Gyuumaoh stands as a warm, comedic, and steadfast figure who evolves from a minor antagonist into a beloved fixture of Son Goku's extended family.