Retired Mexican pro wrestler Rey Misterio Sr., the uncle and trainer to WWE star Rey Mysterio, has died at age 66. His death was confirmed Friday by Mexican wrestling promoter Lucha Libre AAA Worldwide and members of his family. “Eternally grateful for you,” Mysterio’s daughter Aalyah Gutierrez wrote on Instagram. “Without you, my dad wouldn’t be the person or fighter he is today. Rest in peace, uncle.” The circumstances surrounding Misterio Sr.’s death were not immediately made clear, though it comes just weeks after the death of Mysterio’s father, Robert Gutierrez. Born Miguel Ángel López Díaz, Misterio Sr. was well-known in Mexico’s lucha libre scene and also wrestled in Pro Wrestling Revolution, Tijuana Wrestling and the World Wrestling Association (WWA). The two-time IWC World Middleweight Champ wrestled his last match in 2023, capping off a nearly 50-year career that began in 1976. Misterio Sr.’s success extended to that of his mentees. In addition to his three-time WWE world champion nephew, he trained the likes of Konnan, Psicosis, Halloween and Damian 666. “In his heyday, he was almost like Tijuana’s version of Jerry Lawler in Memphis,” Wrestling Observer founder Dave Meltzer wrote on social media Friday. “As a trainer, his track record matches the best.”