Jango Fett, played by Temuera Morrison in Episode II, was famed for being the best bounty hunter in the galaxy in the last years of the Old Republic. About ten years before the Old Republic fell, Darth Tyranus approached the legendary hunter, offering a considerable sum of credits in exchange for Jango's becoming the template for a clone army. These clone soldiers would be grown at an accelerated rate in order to have the army ready in ten years. Fett agreed, but on the condition that he would be given an unaltered clone of himself as well. So Jango disappeared from the bounty hunting scene for the next ten years to raise his cloned son, Boba, on Kamino.

Trade Federation Viceroy Nute Gunray approached Jango to eliminate bothersome senator Padme Amidala. Jango handed off the job to a shapeshifting assassin named Zam Wesell. Unfortunately for Jango, Jedi Obi-Wan Kenobi and Anakin Skywalker interfered and he was forced to kill Wesell himself so the Jedi would not be able to track him through her. He hadn't counted on Obi-Wan's persistence and was forced to flee from Kamino to Geonosis with his son. This was where Jango would pass his Mandalorian armor (which covered scars and tattooed forearms), jetpack, and ship, Slave I to his son when he was killed by Jedi Master Mace Windu. Boba later earned the same reputation as his father.

Source: the official Star Wars site