Oscar Gutierrez is an American professional wrestler signed to WWE. Gutierrez was trained by his uncle Rey Misterio, Sr., learning the Lucha Libre high flying style that has been his trademark.
Gutierrez originally worked for Asistencia Asesoría y Administración in Mexico, from 1992 to 1995. He wrestled in Extreme Championship Wrestling from 1995 to 1996 and World Championship Wrestling from 1996 to 2001, as Rey Misterio, Jr. or Rey Mysterio, Jr. but dropped the "Junior" from his name when he began working for WWE in 2002.
Mysterio is known for having a high flying style, which helped kick-start the cruiserweight wrestling revolution in the United States in the late 1990s during his time in WCW, and is often regarded as one of the greatest high-flyers in wrestling history. In WCW he won the WCW World Tag Team Championship three times, and the WCW Cruiserweight Tag Team Championship once with Billy Kidman as part of the Filthy Animals. In WWE, Mysterio is a three-time world champion, having held the World Heavyweight Championship twice and the WWE Championship once, and is currently listed as the lightest world champion in WWE history.