Jeremy Ethier (Built with Science)

Jeremy Ethier's edge is production, not personality: 3D muscle animations and EMG readouts that make sports science legible to someone who has never opened a journal. His 'best exercises for each muscle' series — biceps, chest, back, shoulders — became the default search result for a reason, racking up hundreds of millions of views between them. Built with Science now ships an app alongside the channel, which is either the natural endpoint of a research-first creator or a sign the free-YouTube-fitness-advice era is ending. Either way, roughly 6 million subscribers aren't complaining.