Leo Vieira is a two-time ADCC World Champion (2003, 2005) and IBJJF World Champion, considered one of the best lightweight competitors in BJJ history. Known for his technical creativity and competitive longevity, he returned from retirement in 2011 to earn an ADCC silver medal at age 36. As co-founder of Checkmat, Vieira has mentored world champions including Marcus 'Buchecha' Almeida and Lucas Leite.