The National Football League (NFL) is one of the most-watched sports leagues on Earth, with millions of passionate fans in almost every corner of the world.

Although the season only runs from September through to February, the NFL has the highest average attendance of any sport in North America. The showpiece culmination of the season, the Super Bowl, is one of the most-watched events in the world.

But, like every sport, the glamour and the glory comes with no shortage of controversy, and there have been a number of occasions when some incredible incidents have thrown the NFL world into shock.

Here are five of the best:

1. Spygate

In 2007, the New England Patriots were at the top of the NFL tree. They had won the Super Bowl three times in just five years (2001, 2003, 2004) and in 2007 they went through the entire regular season without losing a game. In fact, they went all the way to the Super Bowl where they suffered their only defeat of the season by the New York Giants. But that was not to be the only disappointment. During a game between the Patriots and the New York Jets earlier in the season, a number of Jets’ staff reported Patriots head coach Bill Belichick for what they felt was the recording of hand gestures made between Jets’ defensive coaches and players. After a long-running investigation, the Patriots were found guilty of breaking NFL regulations. Belichick was forced into the embarrassing admission of guilt and was fined $500,000, then a record fine in the NFL. The Patriots themselves were also fined $250,000 and they lost their first-round pick in the 2008 draft. What did more damage was that Belichick went on to confess that the franchise had been using similar tactics since the year 2000, which cast a shadow over their run of previous Super Bowl wins.

2. The Adrian Peterson scandal

Peterson was a superstar running back for the Minnesota Vikings when, in 2014, he was prevented from playing in the NFL after being accused of whipping his 4-year-old son – he was indicted on charges of reckless injury to a child. It was an extraordinary fall from grace for a player who had been popular with fans but having been banned from the NFL indefinitely, Peterson pleaded no contest to the lesser charge of reckless assault. He was allowed to return to the Vikings, albeit on a vastly reduced contract.

3. Concussion – the NFL settle 

The discussion around the physical damage the sport has inflicted on players had rumbled on for years. But it was not until 2011, when the tragic news broke that Dave Duerson, a former Pro Bowl safety, had shot himself that the discussion was forced into the public eye. Duerson had texted his family before he shot himself, asking that his brain be analysed by experts to assess whether his problems had been caused by a series of concussions he had suffered during his NFL playing career. Doctors and scientists found Duerson had indeed been suffering from a condition called chronic traumatic encephalopathy, a degenerative disease which was then found to be present in growing numbers of retired NFL players. The league had long dismissed suggestions it had failed to look after former players and manage their health, but a year later the suicide of former player Junior Sea, coupled with a series of pending law suits against the NFL, forced the league to reach a $765 million concussion settlement.

4. Deflategate

Patriots QB Tom Brady – Photo by: Getty Images

Perhaps the most famous controversy of them all and another involving the Patriots. It began when MVP quarterback Tom Brady was found guilty, after an NFL investigation, of asking for his footballs to be slightly underinflated to allow him to grip them more comfortably and throw them more accurately during a crucial AFC championship game.

Brady was suspended for four games for his role in the controversy, the Patriots were fined $1 million, another record fine, and were forced to give up two more draft picks. That was not the end of the matter, however. While the Patriots did not appeal the charges, Brady did. He and his lawyers appeared in front of an appeal hearing after which his four-game ban was overturned.

5. Michael Vick jailed

Michael Vick was the all-conquering college quarterback destined for great things in the NFL. During his time at Virginia Tech, he dominated the opposition with his dynamic running and athletic passing. But having been drafted by the Atlanta Falcons, Vick’s life began to unravel. In 2007 a search of his home found he had been hosting a dogfighting ring on his sprawling Virginia property. Police investigators found injured and wounded dogs at the house, which had been forced to fight. Many others were malnourished. The quarterback was sentenced to almost two years in prison. He was also ordered to pay $1 million towards helping the dogs to recover from their injuries and be rehomed. Before the discovery, Vick had a contract worth almost $140 million with the Falcons. The franchise made Vick pay a fine of almost $20 million.