Celaleddin Koçak (born 24 November 1977 in West Berlin, West Germany) is a Turkish footballer. He began his career at Tennis Borussia Berlin but found little success there. Like many young footballers born to Turkish immigrant parents in Germany, he tried his chances by joining a Turkish team. In December 1999, he decided to join Altay S.K. of İzmir. Six months later he had been impressive enough to earn a place at Süper Lig side MKE Ankaragücü. He stayed there for two years, joining Diyarbakırspor in 2002. Here he helped the newly promoted side to remain in the top division.