A sports rivalry is intense competition between athletic teams or athletes, affecting participants, management, and supporters all to varying degrees. The intensity of the rivalry can range anywhere from a light hearted banter to serious violence. A rivalry that gets out of control can lead to fighting, hooliganism, rioting and some instances with career-ending and even fatal consequences. In the "Football War", along with other factors, it was suggested to have been the tipping point in leading to military conflicts. One of the first known sports rivalries occurred in the Roman Empire between the Blues and the Greens, and the minor teams of the Reds and Whites, each of which were chariot racing clubs competing at the Hippodrome in Constantinople. The rivalry took on political tones as well, coming close to deposing the Roman Emperor Justinian in 532 CE in a riot and the suppression of the riot killed tens of thousands of people. Owners have been known to encourage rivalries as they tend to improve game attendance and television ratings for rivalry matches. Clubs can reduce fan aggression surrounding rivalry games by acknowledging rather than downplaying the conflict because the rivalry is an integral part of fan identity. Games between two rivals that are based in areas of close geographical proximity are often known as a local derby, or simply just a derby ; a sporting event between two teams from the same town, city or region. The term is usually connected with association football and the media and supporters will often refer to this fixture as "Derby Day". The term 'Derby' or local derby originated from a game of football between all saints and St Peter's in the city of Derby. Due to the close proximity of the two churches and hence the football played, this is where the term 'local derby' or "derby" comes from. The term "derby" possibly originated from the Derby, a horse race in England, founded by the 12th Earl of Derby in 1780. The 19th Earl has since claimed the Derby name was originally only given to one other sporting event: fixtures between St Helens at one end of the family's Knowsley estate and Wigan at the other. The other theory as to the name's origin involves Shrovetide football, an early, unofficiated version of both association and rugby football. It was first played in the town of Derby prior to Medieval times. From as early as the 12th century it was known to have been played in Ashbourne. It was a chaotic and exuberant affair that involved the whole town, often resulting in fatalities. The goals were at Nuns Mill in the north and the Gallows Balk in the south of the town, and much of the action took place in the River Derwent or the Markeaton Brook. Nominally the players came from All Saints' and St Peter's parishes, but in practice the game was a free-for-all with as many as 1,000 players. A Frenchman who observed a match in 1829 wrote in horror, "if Englishmen call this play, it would be impossible to say what they call fighting". Shrovetide football is still an annual event in the town of Ashbourne. Since at least as early as 1840 'derby' has been used as a noun in English to denote any kind of sporting contest. Other names for derbies include Clásicos in certain parts of the world and crosstown rivalries in the United States. Rivalries do not always stem from the sharing of an area. Hostilities can occur for different reasons, such as in the case of El Clásico with tensions between fans with a background of political differences. Frequent meetings in important games between teams can also lead to unpleasantries.

International rivalries

Association football

Athletics

Individual

Team

Australian rules football

Badminton

Bandy

In Swedish bandy, derby games are often played on Saint Stephen's Day.

Baseball

Dominican Republic

Dominican Professional Baseball League

Japan

Nippon Professional Baseball

Central League

Pacific League

South Korea

KBO League

Taiwan

Chinese Professional Baseball League

Mexico

Mexican Baseball League

Mexican Pacific League

United States/Canada

Major League Baseball

Minor League Baseball

Venezuela

Venezuelan Professional Baseball League

Basketball

Argentina

Australia

Croatia

China

Guangdong has 11 CBA league titles, more than any other team in history, so it is very evident that they would have a lot of rivalries within the CBA.

France

Germany

Greece

Hong Kong

These are active Hong Kong A1 rivalries: These are high school sports rivalries, but are primarily contested in basketball:

Israel

Italy

Japan

Korea Republic

Lebanon

Lithuania

North Macedonia

Philippines

These are active Philippine Basketball Association (PBA) rivalries: These are the historical rivalries in the PBA: These are active Maharlika Pilipinas Basketball League rivalries: These are college sports rivalries, but are primarily contested in basketball:

Poland

Russia

Slovenia

Serbia

Spain

Taiwan

Taiwan Professional Basketball League

Turkey

United Kingdom

United States and Canada

National Basketball Association

Individuals

Bobsleigh

Bodybuilding

Boxing

Individual

Team

Chess

College sport

Cricket

International

Domestic

Cue sports

Curling

Cycling

Darts

Diving

Esports

Field hockey

Figure skating

Golf

Gridiron football

American football

Individual

College football

Mexico

ONEFA/CONADEIP (National College Association of American Football/National College Sports Commission of Private Institutions)

United States

Canada

Canadian football

Gymnastics

Handball

Austria

Belarus

Belgium

Croatia

Denmark

France

Germany

Israel

Hungary

North Macedonia

Poland

Lomza Vive Kielce vs. Orlen Wisla Plock

Portugal

Romania

Russia

Serbia

Slovenia

Spain

Sweden

Ukraine

Horse racing

Ice hockey

Multinational

Kontinental Hockey League

North America

National Hockey League

Pittsburgh Penguins vs. Philadelphia Flyers

ECHL

Junior

Canadian Hockey League

College

Europe

Austria

Czech Republic

Finland

France

Germany

Italy

Norway

Poland

Romania

Slovakia

Sweden

Switzerland

United Kingdom

International

Individual

Lacrosse

Luge

Mixed martial arts

Other martial arts

Lethwei

Judo

Sumo

Motorsport

Manufacturers, cars, teams

Drivers and riders

Mountaineering and rock climbing

Netball

Rugby league

Australia

National Rugby League

State of Origin

United Kingdom

International Rugby League

Individual

Rugby union

Club Rugby Union

Australia

Argentina

Costa Rica

France

Ireland

Italy

Spain

New Zealand

Poland

United Kingdom

International Rugby Union

Sailing

Short-track speed skating

Skiing

Alpine skiing

Biathlon

Cross-country skiing

Ski jumping

Motorcycle Speedway

Poland

Scotland

Surfing

Swimming

Tennis (Open era only)

Volleyball