The most dangerous
Founded in 1948, the Hell’s Angels motorcycle club has definitely had a worse reputation than any other club we have mentioned. They are also probably the largest club on the planet as well, having thousands of members internationally. Of course not all of them are bad, but there are small fractions within the club that are.
Technically they have been labeled as an organized crime syndicate by the US department of justice because of their involvement with violence, drug trafficking, and other activities. While there are many other groups out there that have been known to be troublesome, the Hell’s Angels are by far the most infamous.