In June 2002, we started see promos hyping the arrival of the "Giant Killer" to World Wrestling Entertainment. He finally made his appearance to the WWE, where he defeated rival Chavo Guerrero.
A short time later, he teamed with John Cena and Edge (yes, the two actually liked each other one lifetime ago) in a storyline involving the three against the Un-Americans (William Regal, Test, Christian and Lance Storm).
Following the brief storyline, and short battle with Kurt Angle, Mysterio would join forces with Edge to defeat Angle and Chris Benoit to snag his first ounce of gold in the WWE, the WWE Tag Team Championships.
After losing the gold to Los Guerreros (Chavo and Eddie Guerrero), Mysterio began focusing on the Cruiserweight Championship and a storyline involving Mr. Era of Mattitude, Matt Hardy.
After a lengthy rivalry, Mysterio finally defeated Hardy to gain the gold in June of 2003. On New Year's Day in 2004, Mysterio defeated Tajiri to lay claim to the Cruiserweight Championship for the second time.
Mysterio would later on challenge Eddie Guerrero for the WWE Championship following WrestleMania XX. Though he lost, he and Eddie's moments together would be far from over.
Following several reigns as Cruiserweight Champion (including a record setting eighth reign after defeating Chavo Classic), Rey returned to tag team wrestling, and alongside Rob Van Dam, he won yet another WWE Tag Team Championship.
Following Van Dam's injury, Mysterio teamed with Eddie to win the gold from The Basham Brothers at No Way Out. At WrestleMania 21, the duo faced each other in arguably one of the best matches in WM History.
The two had some fierce battles during their war, but it was a devastating Twist of Fate that would turn Rey Mysterio into the biggest hero in WM History...