Goku

Goku is the founding father of the Earth Special Forces and one of the lead protagonists of Dragon Ball Zero. Throughout the series, Goku's alcoholism worsens and coincidentally enough, that is how he meets new characters and bonds with them. Goku also hosts a barbeque every so often and serves as the centralized hub for the other Saiyans to keep in contact with one another.

Despite his unassuming power level, Goku contains two of the most powerful finishing maneuvers of the entire team (being the Spirit Bomb and the Dragon Fist), and has a miraculous recovery rate as well as gaining an unprecedented boost in power from each transformation.

Ability
Tier IV [Support, Time Buyer, Finisher]

Primary Martial Art: Tai Jutsu, followed by Aikido, Dragon [Divine]. He is a puncher who occasionally will use ki blast barrages and finishing moves

Biography
Kakarotto Valdez was born on the planet Bejita-sei on an unspecified year with a diminutive power level. As was customary, he was sent to Earth in much the same way that we all have come to know. However, Grandpa Gohan raised him as a Chinese monk and kept him away from city life, fearful that it would be his undoing.

As Grandpa Gohan aged and fell sick, Goku needed to provide for the house and used his incredible strength and limitless stamina to help keep their way of life going by working in the city. Soon, he began attending school there as well and - despite looking like a total outcast in his traditional Buddhist attire, his purity of spirit and single-mindedness won the attention of the popular Chi Chi Yán, who later invited him to a party where she introduced him to alcohol and they had a drunken one-night stand that subsequently resulted in her pregnancy with his first son, Gohan. Both dropped out of school in shame and didn't speak to each other for years.

Story
Goku, now into his adult years, receives a text message from Chi Chi.

Trivia
Goku ends up being the character that introduces most of the Saiyans to the planet while drinking at a bar (which he never does outside of meeting a new character). This is a play off of the beginning of the joke, "So a man walks into a bar..."