KSI

Olajide Olayinka Williams "JJ" Olatunji (pronunciation born 19 June 1993), known professionally as KSI, is a British influencer, musician, and former professional boxer. He is a co-founder and former member of YouTube group the Sidemen, the co-founder of Misfits Boxing and co-owner of several businesses, including Prime Hydration and Lunchly. KSI has also served as a judge on Britain's Got Talent since 2025.

Born in London to parents of Yoruba heritage and raised in Watford, KSI was privately educated at Berkhamsted School. He registered the YouTube channel KSIOlajidebt in 2009 and built a following through his commentary videos of the FIFA video game series. His content later diversified to include vlogs and comedic skits. In 2019, he was ranked second by The Sunday Times in its list of most influential online creators in the United Kingdom. In 2021, he was listed in the Europe Entertainment category of Forbes 30 Under 30; he was later ranked by Forbes as the second-top creator of 2023. As of April 2026, he has over 46 million subscribers and 16 billion video views across his four active YouTube channels.