MONZA, Italy, Sept 1 (Reuters) - Brazilian Felipe Massa announced on Thursday that he will retire from Formula One at the end of the season.

The 35-year-old Williams driver, who won 11 races for Ferrari between 2006 and 2008 and finished overall runner-up to Lewis Hamilton in the 2008 world championship, is out of contract at the end of the year.

"After 15 years in Formula One...this will be my last season," Massa told reporters at the Italian Grand Prix.

Massa, who survived a near-fatal head injury in Hungarian Grand Prix qualifying in 2009, joined former champions Williams from Ferrari in 2014.

(Reporting by Alan Baldwin, editing by Tony Jimenez) ((alan.baldwin@thomsonreuters.com; +442075427933; Reuters Messaging: Reuters Messaging: alan.baldwin.reuters.com@thomsonreuters.net))