1. Fußball-Club Köln 01/07 e. V., better known as simply 1. FC Köln (German pronunciation: [ɛf ˈt͡seː ˈkœln]) or FC Cologne in English, is a German professional football club based in Cologne, North Rhine-Westphalia. It was formed in 1948 as a merger of the clubs Kölner Ballspiel-Club 1901 and SpVgg Sülz 07. Köln compete in the first-tier Bundesliga after winning the 2024–25 2. Bundesliga season and plays its home matches at RheinEnergieStadion.

1. FC Köln was formed in 1948 through the merger of Kölner BC 01 and SpVgg Sülz 07, two successful local sides. It was a founding member of the Bundesliga in 1963 and was crowned its inaugural champions the following year. The club enjoyed golden eras in the 1960s and 1980s, winning three national championships and four DFB-Pokal titles; this includes the inaugural Bundesliga and a domestic double in 1978. After a decline beginning in the 1990s, Köln became known as yo-yo club due to frequent promotions and relegations between the top two tiers. A resurgence in the 2010s brought European qualification and financial stability, but recent seasons have been marked by relegation struggles.

The club is nicknamed Die Geißböcke (The Billy Goats) in reference to its mascot, a male goat named Hennes after veteran Köln player and 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's longest-standing and fiercest rivalry is with Borussia Mönchengladbach, against whom they contest the Rhine derby. Although Mönchengladbach is not located along the Rhine, both clubs are based in the Rhineland cultural region. Köln also shares rivalries with two other Rhineland-based clubs: 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 150,000 members, making it the fourth largest club in Germany.