Rey Mysterio has a reputation for being the Ultimate Underdog, and he certainly fits that description. Mysterio has a diminutive stature, but he makes up for that inside the ring with his speed and outstanding in-ring ability. Mysterio has wrestled in several wrestling promotions, but most of his success has come during his time in WCW and WWE. Mysterio is a sure-fire WWE Hall of Famer, and his record is outstanding. He's a three-time WWE World Champion, a two-time Intercontinental Champion, and a two-time United States Champion, and he has won multiple Tag Team Championships among other titles.

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Mysterio has had a brilliant wrestling career, and whilst he is coming toward the end of his career, he still has a lot to offer. Mysterio has done a good job when he has held a championship, but some of his championship reigns in WWE and WCW were underwhelming.

10 Worst: WWE Tag Team Championship - 4th Reign (2005)

Batista & Rey Mysterio v Kane & Big Show Armageddon 2005 Cropped

Rey Mysterio and Batista both had a good friendship with the late Eddie Guerrero which saw Mysterio and Batista united as one. On the December 16, 2005, edition of SmackDown, Mysterio and Batista defeated MNM for the WWE Tag Team Championship.

This was Mysterio's fourth run as a WWE Tag Team Champion with four different partners, and Batista was a double champion as he was the reigning World Heavyweight Champion. Mysterio and Batista feuded with Raw's World Tag Team Champions Kane and Big Show, and they lost to the gigantic duo at Armageddon 2005. Their title run only lasted two weeks as they dropped the title back to MNM.

9 Best: Intercontinental Championship - 2nd Reign (2009)

Rey Mysterio Intercontinental Champion 2nd Reign Cropped

Rey Mysterio was looking to regain the Intercontinental Championship from Chris Jericho at The Bash 2009. There was another caveat as Mysterio would unmask if he failed to beat Jericho for the Intercontinental Championship. Mysterio and Jericho knocked it out of the park in one of the best Intercontinental Championship matches in WWE history.

Mysterio became a two-time Intercontinental Champion with a victory over Jericho. Mysterio held the gold for 65 days, and he successfully defended the title against Dolph Ziggler at Night of Champions 2009 and SummerSlam 2009. His title run was halted by John Morrison on the September 4, 2009, taping of SmackDown in an underrated clash.

8 Worst: WCW Tag Team Championship - 2nd Reign (1999)

Rey Mysterio & Konnan WCW Tag Team Champions Cropped

On the October 18, 1999, edition of Nitro, the Filthy Animals' Rey Mysterio and Konnan defeated Harlem Heat for the WCW World Tag Team Championship. This was a big deal as Harlem Heat are arguably the greatest Tag Team Champions in the history of WCW.

Unfortunately, Mysterio's second run as a WCW World Tag Team Champion was over before it could gain any traction. He sustained a legitimate leg injury which forced him to relinquish the title, less than a week later at Halloween Havoc 1999.

7 Best: WWE Cruiserweight Championship - 6th Reign (2003)

Rey Mysterio WWE Cruiserweight Champion 1st Reign Cropped

Rey Mysterio finally won his first singles championship in WWE, when he beat Matt Hardy for the WWE Cruiserweight Championship in the main event of the June 5, 2003 taping of SmackDown. This was Mysterio's sixth run as Cruiserweight Champion but first with the title in WWE's possession.

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Mysterio consistently defended the title on SmackDown, and he managed to hold the gold for 112 days. He successfully retained the title against the likes of Hardy, Nunzio, Shannon Moore, and Tajiri. The Japanese Buzzsaw eventually curtailed Mysterio's Cruiserweight Championship reign in September 2003.

6 Worst: WWE United States Championship - 1st Reign (2019)

Rey Mysterio United States Champion 1st Reign Cropped

There's never a timely manner to sustain an injury, but it's worst when you have a championship. Mysterio made it third time lucky when he toppled Samoa Joe for the United States Championship at Money in the Bank 2019. This was Mysterio's first reign as United States Champion, and he became the 21st Grand Slam Champion in WWE history.

The Ultimate Underdog has had his fair share of injuries throughout his WWE career, and his US Championship reign lasted 15 days. He relinquished the championship back to Samoa Joe which was an admirable thing to do.

5 Best: WCW Cruiserweight Championship - 5th Reign (1999)

Rey Mysterio WCW Cruiserweight Champion 5th Reign Cropped

Rey Mysterio continued his love affair with the WCW Cruiserweight Championship when he clinched the title for the fifth time on the April 26, 1999 edition of Nitro. He defeated Psicosis for the championship. Mysterio had an excellent run as Cruiserweight Champion with his final Cruiserweight Championship reign in WCW lasting 115 days.

Mysterio failed to defend the title on pay-per-view, but it was still a good title reign. He overcame the likes of Evan Karagias, Lash LeRoux, and Blitzkrieg but Lenny ended his title run four months later on an episode of WCW Thunder.

4 Worst: WWE Championship - 1st Reign (2011)

Rey Mysterio WWE Champion 2011 Cropped

On the July 25, 2011, episode of Raw, Rey Mysterio, and The Miz slugged it in the tournament final to crown a new WWE Champion. CM Punk "walked" out of WWE as the WWE Champion at Money in the Bank 2011 which is why a tournament was held. Nevertheless, Mysterio captured his third and most recent World Championship reign, which saw him win the WWE Championship for the first time at Miz's expense.

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Mysterio's WWE Championship reign wasn't long for this world as John Cena invoked his rematch clause in the main event. Big Match John ended Mysterio's WWE Championship reign to kickstart another run as WWE Champion, but Punk returned at the end of the show to resume his feud with Cena with both men recognized as WWE Champions.

3 Best: World Heavyweight Championship - 1st Reign (2006)

Rey Mysterio World Heavyweight Champion Cropped

Rey Mysterio's World Heavyweight Championship victory over Kurt Angle and Randy Orton at WrestleMania 22 was one of the most emotional title changes in the history of WrestleMania. The Master of the 619 dedicated his victory to the late Eddie Guerrero. Mysterio wasn't booked strongly as World Champion, but he still had a decent run with the strap.

Mysterio saw off the likes of Randy Orton, JBL, Sabu, and Mark Henry in his 112-day stranglehold as World Heavyweight Champion. At The Great American Bash 2006, Mysterio was betrayed by Chavo Guerrero which led to King Booker dethroning Mysterio to become World Heavyweight Champion.

2 Worst: WCW Cruiserweight Tag Team Championship - 1st Reign (2001)

Rey Mysterio & Billy Kidman WCW Cruiserweight Tag Team Champions Cropped

The inception of the WCW Cruiserweight Tag Team Championship was too little, too late. The title was introduced in February 2001, but that was a month before WCW was going to be purchased by WWE. At Greed, Elix Skipper and Kid Romeo beat the Filthy Animals' Rey Mysterio and Billy Kidman in the tournament final.

Eight days later on the final episode of Nitro, Mysterio and Kidman beat Skipper and Romeo for the titles. Mysterio and Kidman's title reign was dead in the water since WWE didn't opt to keep the championships.

1 Best: WCW Cruiserweight Championship - 1st Reign (1996)

Rey Mysterio Cruiserweight Champion Cropped

Rey Mysterio is one of the greatest Cruiserweight Champions, and he relished the challenge of beating Dean Malenko for the WCW Cruiserweight Championship on the July 8, 1996, edition of Nitro. Mysterio defended the title no fewer than 13 times.

Mysterio retained the title against Ultimo Dragon in his first title defense on pay-per-view at Hog Wild. He also saw off the likes of Malenko, Juventud, and Billy Kidman in television championship bouts. Mysterio had a fantastic run as WCW Cruiserweight Champion which allowed Mysterio to cement his spot at the top of the division, but Malenko recaptured the gold from him at Halloween Havoc 1996.