1. Fußball- und Sportverein Mainz 05 e. V., usually shortened to 1. FSV Mainz 05, Mainz 05 or simply Mainz, is a German sports club, founded in 1905 and based in Mainz, Rhineland-Palatinate. 1. FSV Mainz 05 have played in the Bundesliga, the top tier of the German football league system, for ten consecutive years, starting with the 2009–10 season. The club's main local rivals are Eintracht Frankfurt and 1. FC Kaiserslautern. In addition to the football division, 1. FSV Mainz 05 have handball and table tennis departments.
A failed attempt to start a football club in the city in 1903 was followed up two years later by the successful creation of 1. Mainzer Fussballclub Hassia 1905. After a number of years of play in the Süddeutschen Fußballverband , the club merged with FC Hermannia 07 – the former football side of Mainzer TV 1817 – to form 1. Mainzer Fussballverein Hassia 05, which dropped "Hassia" from its name in August 1912.