Daniel Holý (Ragnar) is a Czech BJJ black belt under Fernando Araújo who teaches no-gi at Jungle BJJ Praha and is widely known online as @ragnar_bjj for leg-lock breakdowns and match analysis. Public academy trainer pages and his own Ragnar Academy materials support that teaching and content focus.

Open BJJ lists him for social discovery with links to Jungle BJJ Praha and related leg-entanglement technique pages. Follower counts are curated approximate snapshots, not live API data.