1. Fußball-Club Köln 01/07 e. V., commonly known as simply FC Köln ([ɛf ˈt͡seː ˈkœln] (listen)) or FC Cologne in English, is a German professional football club based in Cologne in North Rhine-Westphalia. It was formed in 1948 as a merger of the clubs Kölner Ballspiel-Club 1901 and SpVgg Sülz 07. Köln competes in the Bundesliga after promotion in 2018–19 following relegation to 2. Bundesliga the previous season. The team are two-time top-flight champions, winning the Bundesliga in 1964 and 1978. The team plays its home matches at RheinEnergieStadion.

The club's nickname Die Geißböcke (The Billy Goats) refers to the club's mascot, a male goat named Hennes after the veteran FC player and later manager Hennes Weisweiler. The first Hennes was donated by a circus entrepreneur as a Cologne carnival joke. The current mascot is Hennes IX as of 1 August 2019 after Hennes VIII was retired by the club due to old age. Another nickname for the club, more common locally due to its ambiguity, is FC (often written as Effzeh), a common German abbreviation for football clubs. Characteristic for the dialect spoken around Cologne, this is pronounced "EF-tsay", in contrast to the Standard German pronunciation of the abbreviation where the second syllable is emphasized ([ʔɛf ˈtseː]). Köln play at home in white and red, both colours having been used as the main shirt colour throughout its history. The club has long-standing rivalries with nearby clubs Borussia Mönchengladbach, Fortuna Düsseldorf, and Bayer Leverkusen.

Like many of Germany's other professional football clubs, 1. FC Köln is part of a larger sports club with teams in other sports like handball, table tennis and gymnastics. 1. FC Köln has over 100,000 members, making it the fourth largest club in Germany.

Kölner BC was formed on 6 June 1901 by a group of young men who were unhappy as part of the gymnastics club FC Borussia Köln and far more interested in football. BC was a competitive side in the Zehnerliga West in the years before World War I who took the Westdeutsche championship in 1912 and advanced to the preliminary rounds of the national finals. Their next best result was a losing appearance in the 1920 league final, where they lost 1–3 to Borussia Mönchengladbach.