Daniel Engler is an American professional wrestling referee, who is signed to WWE on the Raw brand. He is also known for his work in Total Nonstop Action Wrestling (TNA) under the ring name Rudy Charles, where he was the promotion's senior referee.

In professional wrestling, a referee is an authority figure present in or near the ring during matches. The referee's purpose is similar to that of referees in combat sports such as boxing or mixed martial arts, that is, as an arbiter of the rules and the person charged with rendering decisions. In reality, the referee is, like the wrestlers, a participant in executing a match in accordance with its script including its pre-determined outcome, and is responsible for controlling the flow of the match and for relaying information or instructions from backstage officials to the wrestlers. Like wrestlers, referees are also responsible for maintaining kayfabe, and must render decisions in accordance with the promotion's kayfabe rules.