Diogo Reis "Baby Shark"

Diogo Reis grew up in Manaus, Brazil, and started training Brazilian Jiu-Jitsu in 2012 after his older brother took up the sport. He joined Melqui Galvão's academy as a yellow belt in 2015 and spent the next several years working his way through every colored belt under Galvão's instruction, developing the speed and technical precision that would come to define his career.

Reis announced himself as a generational talent well before reaching black belt. In 2019, at the juvenile and colored-belt levels, he completed a sweep of all four of the IBJJF's major tournaments — the World Championship, Pan Championship, Brazilian Nationals, and European Open — a clean run commonly referred to in the sport as the Grand Slam and a feat few competitors ever accomplish at any stage of their career. Melqui Galvão promoted him to black belt on December 13, 2020.

At black belt, Reis built a resume that spanned both IBJJF gi competition and no-gi submission grappling. He medaled at the IBJJF World Championship and Pan Championship in the light-featherweight division across 2022, 2023, and 2025, won Brazilian National titles, and captured the Who's Number One featherweight tournament in 2023. His signature results, however, came in the ADCC World Championship, where he won gold in the −66 kg division in both 2022 and 2024 — back-to-back titles that placed him among the sport's most dominant lighter-weight grapplers.

In March 2025, Reis made his debut for ONE Championship, submitting Shoya Ishiguro with a kimura, and went on to become the promotion's Flyweight Submission Grappling World Champion, extending his career beyond the traditional IBJJF and ADCC circuits into a new stage as a mixed-discipline submission grappling standout.

In 2026, Reis parted ways with the academy that raised him from a teenager to a two-time ADCC champion, amid a widely reported criminal investigation into his longtime coach, Melqui Galvão. He now trains and competes independently. Regardless of team affiliation, his combination of speed, leg-lock proficiency, and willingness to compete up in weight against far larger opponents has kept him among the most closely watched lighter-weight grapplers in the sport.

Nicknamed "Baby Shark" for his small frame paired with an outsized submission threat, Reis is an aggressive, fast-paced leg-lock and guard-passing specialist wh