Željezničar Sarajevo

Fudbalski klub Željezničar Sarajevo (Serbo-Croatian Cyrillic: Фудбалски клуб Жељезничap Сарајево; English: Football Club Željezničar Sarajevo), commonly referred to as Željo, is a professional football club, based in Sarajevo, Bosnia and Herzegovina. The name Željezničar means "railway worker", originating from their establishment by a group of railway workers in 1921. Throughout its history, the club has cultivated a reputation for producing talented home-grown players through its youth school.

During the days of socialist Yugoslavia, FK Željezničar were national champions in the 1971–72 season, qualifying for the European Cup during the 1972–73 season. The club has also finished as runners-up once in the league, and contested 1980–81 Yugoslav Cup final. In Europe, the club reached UEFA Cup semi-finals during the 1984–85 season and the quarter-finals during the 1971–72 season.

Alongside FK Sarajevo, Željezničar is the most successful football team in present-day Bosnia and Herzegovina, having won 6 Bosnian championships, 6 Bosnian Cups and 3 Bosnian Supercups. The club's so far best post-war European result was qualifying to the 2002–03 Champions League third qualifying round, losing to Newcastle United. Their biggest rival is FK Sarajevo with whom they contest the biggest football match in Bosnia and Herzegovina, the Sarajevo derby.