Football hooliganism, also known as soccer hooliganism, football rioting or soccer rioting constitutes violence and other destructive behaviours perpetrated by spectators at association football events. Football hooliganism normally involves conflict between gangs, in English known as football firms (derived from the British slang for a criminal gang), formed to intimidate and attack supporters of other teams. Other English-language terms commonly used in connection with hooligan firms include "army", "boys", "bods", "casuals", and "crew". Certain clubs have long-standing rivalries with other clubs and hooliganism associated with matches between them (sometimes called local derbies) is likely to be more severe.

Conflict may take place before, during or after matches. Participants often select locations away from stadiums to avoid arrest by the police, but conflict can also erupt spontaneously inside the stadium or in the surrounding streets. In extreme cases, hooligans, police, and bystanders have been killed, and riot police have intervened. Hooligan-led violence has been called "aggro" (short for "aggression") and "bovver" (the Cockney pronunciation of "bother", i.e. trouble).

Hooligans who have the time and money may follow national teams to away matches and engage in hooligan behaviour against the hooligans of the home team. They may also become involved in disorder involving the general public. While national-level firms do not exist in the form of club-level firms, hooligans supporting the national team may use a collective name indicating their allegiance.