Damien Anthony Duff (born 2 March 1979) is an Irish professional football coach and former player who played predominantly as a winger and is currently a first-team coach at Shamrock Rovers.
He began his professional playing career with Blackburn Rovers, with whom he won the Football League Cup, and in 2003 was signed for £17 million by Chelsea, where he won two Premier League titles and another League Cup. After four seasons at Stamford Bridge, he left for Newcastle United where he won the 2006 UEFA Intertoto Cup, and then moved on to Fulham, with whom he played in the 2010 UEFA Europa League Final. He ended his career with brief spells in the A-League with Melbourne City and the League of Ireland with Shamrock Rovers before retiring in December 2015. Since then he has moved into coaching, working with the Shamrock Rovers under-15s and first team, and the Republic of Ireland under-15s.
Duff played international football for the Republic of Ireland for 14 years, winning 100 caps between 1998 and 2012. He played at the 2002 FIFA World Cup and captained the country at UEFA Euro 2012.