Ronald Koeman (born March 21 1963 in Groningen) is a former Dutch football defender and now manager.

In 1980 Koeman started his career for FC Groningen, and after playing for Ajax Amsterdam, PSV Eindhoven and FC Barcelona, he finished his career in Feyenoord Rotterdam. During his career he won 4 Dutch championships, 4 Spanish championships, and was also in the winning Dutch national team at the 1988 European Championship. Besides being a sturdy defender at the centreback position for the national team, he was also reknowned for his freekicks and deadball situations where he has scored many vital goals for the team. He also represented his nation in the World Cup 1994 in USA.

From December 2001 until February 2005, Koeman was Ajax Amsterdam team manager. After disappointing results in the Eredivisie and being eliminated in the UEFA Cup, he resigned.