In 2007, The Times placed him at number 11 in their list of the 50 "hardest" footballers in history.In his 18-year playing career, Keane played for Cobh Ramblers, Nottingham Forest and Manchester United, before ending his career at Celtic.
Keane was a dominating box-to-box midfielder, noted for his aggressive and highly competitive style of play, an attitude that helped him excel as captain of Manchester United from 1997 until his departure in 2005.
Keane helped United achieve a sustained period of success during his 12 years at the club.
He then signed for Celtic, where he won a domestic double before he retired as a player in 2006.
Keane played at international level for the Republic of Ireland over a period of 14 years, most of which he spent as captain.
At the 1994 FIFA World Cup, he played in every Republic of Ireland game.
He was sent home from the 2002 FIFA World Cup after a dispute with national coach Mick McCarthy over the team's training facilities.
Keane was appointed manager of Sunderland shortly after his retirement as a player and took the club from 23rd position in the Football League Championship, in late August, to win the division title and gain promotion to the Premier League.
He resigned in December 2008, and from April 2009 to January 2011, he was manager of Championship club Ipswich Town.
In November 2013, he was appointed assistant manager of the Republic of Ireland national team by manager Martin O'Neill.
Keane has also worked as a studio analyst for British channel ITV's football coverage.