Carlos Ruiz is a Spanish professional wrestler currently signed to WWE, where he performs on the NXT brand under the ring name Axiom and is currently one-half of the NXT Tag Team Champions with Nathan Frazer in their first reign. He previously performed in NXT UK as A-Kid, where he was a former one-time and the inaugural NXT UK Heritage Cup Champion. Ruiz also competed in various American and European independent circuits, notably for Pro Wrestling Guerrilla (PWG), Progress Wrestling, and Chikara. In 2018, Ruiz became the first Spaniard and the youngest wrestler at the age of 20 to ever compete in a singles match rated 5 stars by Dave Meltzer of the Wrestling Observer Newsletter. In 2020, Ruiz became the first Spanish wrestler to win a championship in WWE after winning the NXT UK Heritage Cup.