Momochi, Zabuza was born in Kirigakure. During one of Kirigakure's annual events of pitting graduating ninja against each other, Zabuza singlehandedly killed all of his peers, bringing an end to the ritual and causing him to be called the "Demon of the Hidden Mist". Zabuza would go on to become one of the Seven Shinobi Swordsmen of the Mist where he acquired his zanbato, and also became a member of the Kirigakure ANBU. At some point in time, Zabuza found a young boy named Haku wandering the countryside, and offered to take Haku in as his tool. Haku accepted and became loyal to Zabuza, learning from Zabuza and protecting him whenever necessary. Zabuza eventually attempted a coup d'etat on the Land of Water by trying to assassinate the Mizukage. The coup failed, forcing Zabuza and his subordinates to leave the country. In the hopes of gaining funds for a second coup, Zabuza became a hired assassin, killing anyone if the price was right.
Being from Kirigakure, Zabuza excels in water-oriented jutsu, some of which are exclusive to him. With Water Release: Water Dragon Blast Technique (Suiton: Suiryudan no Jutsu, Viz "Water Release: Water Dragon Missile") he can form a dragon from the surrounding water to attack others as needed. His Water Release: Great Waterfall Technique (Suiton: Daibakufu no Jutsu, English TV "Water Style: Giant Vortex Jutsu") allows him to fire a massive spiraling blast of water at an opponent. In addition to the offensive capabilities of his water jutsu, Zabuza is very skilled in assassinations. By blanketing the area in mist with Hiding Mist Technique (Kirigakure no Jutsu, Viz "Art of Hiding in the Mist"), Zabuza can blind an opponent and use his training as an ANBU to find them based on the sounds they make. Once found, Zabuza uses Silent Homicide Technique (Muon Satsujin Jutsu, English TV "Silent Killing Jutsu") to kill the opponent without their noticing his presence. This talent with assassinations is very well-known, as even the ninja of Konohagakure are familiar with Zabuza's history.