Old Firm — Celtic vs Rangers

The Old Firm between Celtic and Rangers is the most attended club derby in the world per capita and has been played over 400 times since 1888. It represents a religious, political, and national divide — Celtic founded by Irish Catholic immigrants, Rangers historically associated with Protestantism and unionism. The match generates some of Europe's most intimidating atmospheres and has historically been associated with sectarian violence that has required sustained policing. Despite Rangers spending four years outside the top flight (2012–16), the fixture's cultural significance never diminished.