The 2004–05 FA Cup was the 124th season of the world's oldest football competition, the FA Cup. The competition began on 28 August 2004, with the lowest-ranked of the entrants competing in the Extra preliminary round. For England's top 44 clubs, from the 2004–05 Premier League and 2004–05 Football League Championship, the FA Cup began at the third round in January.

Leigh Genesis Football Club, formerly known as Horwich Railway Mechanics Institute F.C. and Leigh Railway Mechanics Institute F.C., is an English amateur association football club that currently plays in the South Lancashire Counties Football League. The semi-professional senior side folded in 2011, following relegation from the Northern Premier League; however, the club continued, fielding youth teams in the North West Youth Alliance, and a women's team in the North West Women's Regional League. The senior team was reintroduced for the 2012–13 season in the South Lancashire League.