His flamboyant style made him popular with spectators but drew controversy. His first 250cc win, at Italy's Mugello on June 1, 2008 en route to the title, came after he leaned into Barbera at the end of the long straight.
The pair hit, Barbera crashed and Simoncelli escaped with a verbal warning from the MotoGP Riders Safety Commission.
Further controversy erupted in April 2011 at Estoril, when defending MotoGP champion Jorge Lorenzo - who had an on-track clash with the frizzy-haired Italian at Valencia in November 2010 - said: "I don't like the way he overtakes, he is too aggressive. I can't say anything negative about his speed, he is a very fast rider, a talented rider, but he is too aggressive and most riders think like me."
Then came the Dani Pedrosa crash at Le Mans in May this year while fighting for second which earned Simoncelli a ride-through penalty and criticism he cut across the other rider. Initially writing it off as 'a racing incident' he later admitted: "Overall, on reflection, I have realised where I have gone wrong and in the future I will try at certain times to evaluate the situation better and be a little more cautious."