Thomas Johannessen is a Brazilian jiu-jitsu black belt under Eduardo "Teta" Rios and a long-standing senior instructor at Frontline Academy's Majorstuen headquarters in Oslo. By profession he is a qualified physiotherapist and personal trainer, and he is best known in the BJJ community for combining medical knowledge with grappling expertise in his training and content.
Johannessen and Morten Josephson were the two Norwegians who, in 2006-2007, persuaded Eduardo "Teta" Rios to leave Brazil and settle permanently in Oslo to run the academy. That invitation turned Frontline from a strong local club into an internationally competitive training centre with a clear lineage back to Carlson Gracie and Ricardo Libório.
As a competitor Johannessen has been active on the European IBJJF circuit, representing Frontline at events such as the Rome International Open (2015) and the European Championship. As an educator he has contributed strength-and-conditioning programmes designed specifically for grapplers, technique videos distributed through platforms such as WatchBJJ, and articles on competition preparation — training, conditioning, diet and mindset.
Note: Johannessen is sometimes mis-identified as a 2003 co-founder of Frontline Academy. The original 2003 founders were Trond Saksenvik, Thomas Hytten, John-Olav Einemo and Joachim Hansen. Johannessen's decisive contribution came in the 2006-2007 transition, when the academy brought in Teta Rios and professionalised its operation.
Sources: Frontline Academy instructor page; Smoothcomp profile 1012; MMA Viking; BJJ Scandinavia.