Bayer 04 Leverkusen Fußball GmbH, also known as Bayer 04 Leverkusen, Bayer Leverkusen, or simply Bayer, is a German professional football club based in Leverkusen in the state of North Rhine-Westphalia. The club competes in the Bundesliga, the top tier of German football, and plays its home matches at the BayArena.
The club was founded in 1904 by employees of the German pharmaceutical company Bayer AG, whose headquarters are in Leverkusen and from which the club draws its name. The club's main colours are red and black, both having been used as the main shirt colour and with red and black stripes also having been used as home colours.
Bayer Leverkusen have won one DFB-Pokal and one UEFA Cup. Their local rivals are 1. FC Köln. As of 2020, Bayer Leverkusen is regarded as one of the biggest football clubs in Germany.
In contrast to many other German football clubs, which hold close ties to their working-class roots, Bayer Leverkusen strives for a clean, family-friendly image. The BayArena has the reputation of being one of the most family-friendly football stadiums in Germany.