Alaattin Baydar (1901 – 13 July 1990) was a Turkish football player of Fenerbahçe. Born in İstanbul, he played as a right winger and right forward and was called Alâ. He is brother of Nasuhi Baydar who is one of Fenerbahçe founder.
He played 18 years for Fenerbahçe between 1916-34. He is third goalscorer of Fenerbahçe history with 362 goals in 324 matches and he also scored 24 goals in 39 matches against Galatasaray. He won 1920-21, 1922-23 Istanbul League Championships as player and won 1963-64 and 1964-65 Turkish League Championships as president. He is also member of General Harington Cup squad.
He was a member of first Turkish national football team squad who played against Romania on 26 October 1923. He played 16 times for the national team. He is also member of national team of 1924 and 1928 Summer Olympics