The group originates from a Rockstar Games Social Club group made on 19 October 2013 in Grand Theft Auto Online, called "The Ultimate Sidemen", which included all the members except for Lewis. In January 2014, Bradley met Lewis while at a FIFA gaming event in New York City and invited him to join the group.

Did JJ create the Sidemen?

The Sidemen (also known as SDMN, formerly The Ultimate Sidemen), created on 19 October 2013, are a British YouTube group made up of Zerkaa (Josh Bradley), Miniminter (Simon Minter), TBJZL (Tobi Brown), KSI (Olajide "JJ" Olatunji), Behzinga (Ethan Payne), Vikkstar123 (Vikram Barn) and W2S (Harry Lewis).

How did Harry join the Sidemen?

At the age of 17, he dropped out of school and decided to do YouTube as his full-time job. Harry was the last to join the Sidemen, becoming a member around the same time he dropped out of school in early-2014 (a few months after their formation).