Ali Haydar Şen (born Ali Haydar Maga in 1939 in Prizren, Kingdom of Yugoslavia, now Kosovo) is an ex-president of the Fenerbahçe S.K..
Şen was born to an ethnic Turkish family in Kosovo.
He worked as a journalist for a short time, before he first came to Fenerbahçe in 1975, when he was made head of the club's basketball branch. On April 12, 1981, he was chosen as club president, taking the reins from Razi Trak.
During his first spell as club president, the club's football team won the league and cup double in the 1982-83 season, and his tenure ended on December 10 when he resigned. He had one more spell at the club, from December 1994 through until 1998 with the football side again winning a championship a year after he came to power. He is famous for the then popular chant of club supporters, "Ali Şen başkan, Fenerbahçe şampiyon" (If Ali Şen is president, Fenerbahçe is victorious/champion).
In the 1995-96 season, goals from club legends Aykut Kocaman and Oğuz Çetin against Trabzonspor in the third last game of the season all but sealed the championship for Fenerbahçe. But it wasn't enough to convince Ali Şen, and at the end of the season both players and Emre Aşık were sacked, leading to huge controversy amongst the club's faithful.
In late 1997, he announced that he would not run for third time at the club. Later on presidency has been taken over current supremo Aziz Yıldırım.
^a. Kosovo is the subject of a territorial dispute between the Republic of Kosovo and the Republic of Serbia. The Republic of Kosovo unilaterally declared independence on 17 February 2008, but Serbia continues to claim it as part of its own sovereign territory. The two governments began to normalise relations in 2013, as part of the Brussels Agreement. Kosovo has received formal recognition as an independent state from 111 out of 193 United Nations member states.