The 2008 Six Nations Championship, known as the 2008 RBS 6 Nations because of sponsorship by the Royal Bank of Scotland, was the ninth series of the rugby union Six Nations Championship, the 114th series of the international championship.

Fifteen matches were played over five weekends from 2 February to 15 March, resulting in Wales winning the Grand Slam, their second in the last four championships and tenth overall.

In winning the Grand Slam, Wales also won the Triple Crown, for beating each of the other Home Nations, for the 19th time.

Wales conceded only two tries in the championship, beating England's previous record of four tries conceded.

Wales' Shane Williams was named the Player of the Championship.