Association football remains the sport with the most viewers worldwide. Additionally, it enjoys the strongest backing, sometimes going overboard. Thus, a high cost is linked with that intense love of the game. Even life itself is the worst-case scenario payment for that price. Thus, football has the highest number of violent fan injuries or fatalities. Unfortunately, that has happened much too frequently in games all across the world. Hence competitive spirit cherished in the game is transformed by ultra-fan groups into something entirely else.

10. Barcelona

Although the club has recently come to be associated with class, their Ultras Boixos Nois, or "The Crazy Boys," are everything but civilized. The organization was established in 1981, and up until former president Joan Laporta chose to forbid them from the stadium in 2003, they even had a unique relationship with the team.

When the Ultra gang tore down a banner at Camp Nou honoring Liverpool after the Heysel tragedy, they made a terrible public display of their objectives. For killing a supporter of cross-town rivals Espanyol in 1991, one of the Ultras group's members was given a 26-year prison term, which terrified football supporters across the country.

9. Wisla Krakow

Poland is a nation where football hooliganism and violent fans are commonplace. Fans of Wisla Krakow have a sizable following and have frequently caused trouble. In 1999, Wisla fans were said to have thrown a dagger that allegedly struck Dino Baggio of Parma F.C. in the head. Furthermore, in 2003, Wisla hooligans took part in a five-club brawl in Wroclaw, Poland. 

Due to the constant involvement of fans in lethal drawls, there is almost a guarantee of casualties or fatalities during the semi-annual "Holy War" rivalry game between Krakow and MKS Cracovia. In the 2006 version, a hooligan clash in the city resulted in the deaths of eight people.

8. Ferencvaros FC

Even if the club may not be among the biggest in Europe, the Green Monsters Ultra section ensures they always give their all to support their team. Yet, that often results in incidents.

With the use of baseball bats, chains, and even tasers considered normal in the lead-up to, during, and after their match against their fiercest rivals, the Hungarian club's fans have established themselves as some of the most violent in all of Europe. Therefore, the club even banned them for several years. A game against arch-rivals Ujpest is thought to bring out their monstrous best.

7. Sparta Prague

The most infamous team in central and eastern Europe is A.C. Sparta Prague from the Czech Republic. Their hooligan gangs are among the most organized and sophisticated fan bases in the game, communicating via Facebook or websites.

Sparta fans are not only willing to engage in combat with opposing supporters but also do not fear authority. They have often attacked prominent current or past club members. In 2006, when sections of the 5,000 Scottish visitors got into a fight with Ultras, they attacked former Hearts Chairman George Foulkes.

6. Metalist Kharkiv

The refounded Ukrainian team has some of the most fervent supporters in all sports. However, given how frequently enthusiasm is mistaken for violence, it's not surprising that the club experienced some issues due to the presence of an Ultras group.

The Ultras engaged in many clashes with Dynamo Kyiv, their archrivals, whom they were expected to dethrone as one of the best teams in Ukraine. Fights breaking out over the stadium were not uncommon when the two groups clashed.

5. River Plate

The River Plate of Argentina is well known for having rowdy supporters. Around the club's ultra-fan groups, riots, fighting, and other altercations are commonplace. Hooligan factions from different clubs typically battle each other. However, the ferocious River Plate supporters occasionally lash out at one another.

The argument over where to stand in the stadium ignited their gun and knife brawl in 2007 before a game, which is evidence of this. In the summer of 2012, a club supporter was fatally stabbed following a fight with Boca Unidos supporters. Fox News Latino said the young fan, Gonzalo Saucedo, was only 21 years old.

4. Universitario de Deportes

The Universitario de Deportes in Peru has one of South America's most aggressive fan bases. The club's extremist supporters have set rival supporters' cars and buses on fire, but the worst instance involved throwing an opposition supporter from the stands.

A fan of Universitario rival Alianza, 23-year-old Walter Oyarce Dominguez, was hurled from one of the stadium's top tiers by another supporter in November of 2011. After falling more than 50 feet (15 m) to the pavement below, he suffered head damage and passed away in the following days.

3. Roma

Numerous incidents, including fan violence, stabbings, and ongoing hooliganism and thuggery, have been caused by AS Roma supporters. In Rome, Liverpool supporters were attacked twice in 2001. In 2006, supporters of Middlesbrough were assailed and stabbed. In a subsequent incident with Manchester United in 2007, more foreign supporters were hurt by thugs.

Violence has also occurred in Italy's eternal city due to local conflicts with SS Lazio supporters. Romans were formerly referred to as a "mob," and current Roma supporters can nearly be compared to them because both groups' emotions are based on the success or failure of their team.

2. Millwall F.C.

For many years, Millwall has been a thorn in the side of English football, even though they are among the best London football teams. The young fans became the numerous supporters that gave Millwall its fearsome reputation. Two of their most well-known events featured the loathed neighborhood rivals West Ham United.

These are the 2009 Upton Park Riot and the 1985 Kenilworth Road Riot. The most well-known of their hooligans and thugs groups is The Bushwackers. The group, which typically numbers 200 to 250 people at once, is by far the most ardent follower of the team.

1. Galatasaray

The Galatasaray Ultras, or UltrAslan as they are more commonly referred to, are among the most ardent Ultras in football. The ultrAslan was founded in 2001 when a variety of smaller groups of supporters decided to unite. Since then, they have built an infamous reputation for themselves.

Regardless of their notoriety, the UltrAslan have made life difficult for visitors with choreography and flare use. The phrase "Welcome to Hell" is frequently used to greet visiting teams. The UltrAslan have made sure to live up to their words, not just for the players but also for the visiting spectators.

Football has experienced its share of problems despite consistently mesmerizing us with its positive aspects. The sport, once outlawed in England for being too violent, has not only offered us role models. Instead, it gave us lessons from the illustrious lives of others who achieved prominence via their football prowess and quickly faded due to problems off the field.

What are some of the most infamous football incidents you've heard of? Should organized fan groups be outlawed?

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