Jeffrey Cobb is an American professional wrestler and former amateur wrestler best known for his eight-year run in New Japan Pro-Wrestling (NJPW) from 2017 to 2025, where he was a member of United Empire and became a one-time NEVER Openweight Champion, a one-time NJPW World Television Champion, and a three-time IWGP Tag Team Champion. Cobb made his G1 Climax debut in 2019, competed in six editions of the tournament, and opened the 2021 G1 Climax by winning his first eight matches, a feat unmatched in tournament history. He was ranked No. 23 in the PWI 500 by Pro Wrestling Illustrated in 2019 and won the Tokyo Sports Best Tag Team Award in 2022 alongside United Empire stablemate Great-O-Khan.

Outside of NJPW, Cobb wrestled in Lucha Underground from 2015 to 2018 as the masked wrestler Matanza Cueto, during which he held the Lucha Underground Championship, and also competed for Ring of Honor (ROH), where he won the ROH Television Championship, and Pro Wrestling Guerrilla (PWG), where he captured both the PWG World and World Tag Team Championships and won the 2018 Battle of Los Angeles.

As an amateur wrestler, Cobb represented Guam at the 2004 Summer Olympics, where he served as the nation’s flag bearer and competed in the men’s light heavyweight freestyle category before transitioning to professional wrestling in 2009.

He later signed with World Wrestling Entertainment (WWE) in May 2025, performing on the SmackDown brand under the ring name JC Mateo as part of The MFTs alongside Solo Sikoa, Tonga Loa, Talla Tonga, and Tama Tonga, before departing the company in 2026 following the expiration of his one-year contract.