Football's a game of tribes, passions and loyalties that frequently boils over. Here's a collection of some truly remarkable images featuring flashpoints between ultras and police from both outside and inside stadiums around the world.
A Newcastle United Supporter Punches a Horse
@BoxingBenedict | Twitter
A Legia Warsaw Ultra Hurls a Fence at an Officer in Madrid
@RMadridHome_ | Twitter
Russian Ultras and English Hooligans Clash in France
@SupremeCesc | Twitter
An England Supporter isn't Phased at EURO 2016 in France
@SupremeCesc | Twitter
Rangers Supporters Outside Celtic Park
@Joelrookwood | Twitter
Arsenal vs. Millwall in 1982 at Highbury
@footballmemorys | Twitter
The Barra Brava of Boca Juniors at La Bombonera
@ManuelVeth | Twitter
Supporters in Argentina are Hosed by Police
@Vam0sArgentina2 | Twitter
A Helicopter is Used for Crowd Control in Equatorial Guinea
@AJENews | Twitter
A Legia Warsaw Ultra Uses Pepper Spray on a Steward
@oktranking | Twitter
Russian Hooligans Clash with Police in Shades of Orange and Yellow
@listonline1 | Twitter
The Eternal Derby of Belgrade
@VICEAU | Twitter
The Intercontinental Derby in Istanbul
@cellie_beckie | Twitter
A Riot Squad Rushes a Group of Ultras
@UltrasWorld1312 | Twitter
A Feyenoord Ultra Surveys the Scene
@UltrasWorld1312 | Twitter
Olympiakos Ultras Making Their Presence Known
@UltrasWorld1312 | Twitter
Hidden in the Pyrotechnics
@UltrasTifo | Twitter
Saint-Etienne Supporters Make Their Way to Old Trafford in Manchester
@UltrasTifo | Twitter
CSKA Moscow Supporters Don't Mind the Weather
@UltrasTifo | Twitter
Palmeiras Ultras Clash with Police
@UltrasTifo | Twitter
A Clash in the Netherlands
@HHooligan | Twitter
Classic Case of Man Running from Cops in England
@CasualMind_ | Twitter
Besiktas Ultras Throw Chairs
@HHooligan | Twitter
Hooligans Attack a Police Officer
@HHooligan | Twitter
Police Search a Child
@HHooligan | Twitter
The Tyne-Wear Derby in England
@HHooligan | Twitter
Sao Paulo Supporters Making Their Way to the Morumbi
@HHooligan | Twitter
Saint-Etienne Ultras Flip the Script
@HHooligan | Twitter