Some fucking nobody that would have remained unknown to the rest of the world for his entire life had he not provoked Zinedine Zidane into headbutting him.
Previously in the FIFA World Cup 2006, he got a red card during Italy's match with Australia and was suspended during Italy-Ukraine.
Then during the 2006 World Cup Final (France-Italy), Materazzi for no other reason than being a complete dickhead and with no provocation whatsoever, called Zidane's sister/mother a whore and possibly said things to him of a racist nature.
Zidane put him down like the little, Italian faggot he is, and then watched him cry his eyes out on the pitch while Zidane got a red card for doing what any upstanding, proud and heroic football player would have done.
Unfortunately all the media bullshit and public scandal surrounding the event forced one of the greats of the sport into a somewhat early retirement, however after the full story came out a lot of people became more sympathetic to Zidane's side and forgave him.
Especially after discovering that's it always been Italian tradition in football to fix matches, pay off referees, fake injury and rig games to their liking.