Jango Fett is the father of Boba Fett, who himself is actually an unaltered clone of the senior Fett. Jango was once an innocent farm boy on the colony planet of Concord Dawn until his family was murdered by a band of ruthless mercenaries calling themselves The Death Watch. Jango was saved by the Mandalorian's that his family had been aiding and raised by their leader, Jaster Mereel.
Jango later took over the reigns of leadership when Mereel was killed in an ambush by The Death Watch. Jango would later avenge his leader/adopted father's death but that still could not prepare him for the tragedy that would befall him when his entire group, save for himself, was destroyed by a band of Jedi led by a young Count Dooku. Dooku, himself, would later recruit Jango many years later to be the template for the Republic's Clone Soldiers.
In the years following the annihilation of his Mandalorian brother's, Jango earned his living as a formidable bounty hunter. His talent for tracking down the Galaxies most wanted would later be passed on to his son Boba, who would later earn a reputation more widely known and feared than Jango's.