Espen Mathiesen (born May 10, 1995) is a Norwegian Brazilian jiu-jitsu black belt and one of Europe's most decorated grapplers. Born in Egersund on Norway's west coast, he earned his black belt from longtime coach Jose Carlos of Kimura/Nova Uniao in 2017 after a remarkably successful colored belt career that included IBJJF World and European titles at blue belt and a World Championship silver medal at purple belt.
As a black belt, Mathiesen's crowning achievement came at the 2022 IBJJF European Championship where he won gold in the lightweight division. He also captured the Abu Dhabi World Pro Championship and earned third place at the 2018 IBJJF World Championship. In 2024, he took silver at the European Championship and gold at the Dublin International Open, before winning the 2025 Dublin International Open at light heavyweight.
Mathiesen began training BJJ in Egersund under Damoun Nassehi before relocating to Haugesund to train under Jose Carlos alongside Tommy Langaker and Vegard Randeberg. He spent formative time at Art of Jiu-Jitsu with the Mendes brothers and with Gustavo Dantas in Arizona. Known for his technical innovation, Mathiesen co-developed the matrix guard system with training partner Tommy Langaker. He won the Copa Podio Lightweight Grand Prix and IBJJF Pan American Championship as a brown belt in 2017. A cerebral competitor who emphasizes active drilling and mental preparation, Mathiesen represents the rise of Scandinavian jiu-jitsu on the world stage.