A Bio-android from the future who came back to the past to absorb two androids -17 and 18- to reach his perfected form, and become the strongest.

A Saiyan from Earth, Goku landed on Earth as a baby, where he was taught and raised by 'Grandpa' Gohan. He went on to go through many adventure, learning, growing stronger, and making new friends along the way.
Most recently, he sacrificed himself and those on King Kai's planet to prevent Cell from blowing up Earth. Though, with the Dragonballs, his death isn't exactly permanent, he has requested to stay dead for fear of attracting dangerous people to Earth if he is alive.

The fourth of his name, Vegeta is Prince of the Saiyans who resided on planet Vegeta, before it's destruction when he was 5 years old. 
After that, Vegeta served under the person who destroyed it, Frieza, unaware of the culprit until many years later, and after he met, and lost to, Goku.
Since the defeat of Frieza, Vegeta has remained amicable, settling down on Earth alongside Goku as a rival, and making a child with Bulma Briefs called Trunks.
Most recently, he has been dedicating himself to training after Goku's recent death.

Bio-androids are lifeforms created through the use of technology -gene splicing, stem cell growing, etc.-, but made of entirely biological parts. The most notable part of their unique biology is the fact that each of their cells contain advanced programming in their nuclei, with the most advanced among them being able to use each and every cell as the 'brain' for the whole body, with no difference in memory or function between the cells.
They also tend to be able to be pre-programmed with knowledge (the ability to cook, walk, manipulate ki, etc.)