He moved to WWF during the Attitude Era with his WCW colleagues Chris Benoit, Dean Malenko and Perry Saturn, who formed a group called The Radicalz.

After being rehired in 2002, he formed Los Guerreros with his nephew Chavo, winning the WWE Tag Team Championship, and established himself on the SmackDown brand.

Guerrero then appeared on a televised AAA show as Máscara Mágica, only to then unmask himself along with the aid of his tag team partner that night, Octagón.

[2] Along with Barr, Konnan, Chicano Power, and Madonna's Boyfriend, Guerrero formed los Gringos Locos ("the Crazy Americans"), a villainous stable.

[20] In 1996, Guerrero received several shots at the United States Heavyweight Championship against Konnan at Uncensored[21] and Ric Flair at Hog Wild.

[26] In 1997, Guerrero defended the United States Heavyweight Championship against Scott Norton at Clash of the Champions XXXIV,[27] Syxx in a ladder match at Souled Out,[28] and Chris Jericho at SuperBrawl VII.

These frustrations came to a head when Guerrero requested that WCW President Eric Bischoff either push his character or give him a raise for family reasons.

After his return on the May 31, 1999 episode of Monday Nitro, Guerrero became a founding member of the Filthy Animals alongside Rey Mysterio Jr. and Konnan.

[51] When Vince Russo was fired as WCW booker and replaced by Kevin Sullivan, Guerrero asked for and received a release from his contract on January 19, 2000.

Guerrero, Chris Benoit, Dean Malenko and Perry Saturn debuted in the WWF on the January 31, 2000 episode of Raw is War as The Radicalz, interfering in a match involving The New Age Outlaws, establishing themselves as faces.

[54] Then at SummerSlam on August 27, Guerrero and Chyna wrestled an Intergender tag team match against Trish Stratus and Val Venis, who at the time was the reigning WWF Intercontinental Champion.

[54][64] Benoit left the group to focus on a singles career while the rest of The Radicalz feuded with Lita and The Hardy Boyz (Matt and Jeff).

At Backlash on April 29, Guerrero competed in a Triple threat match for the WWF European Championship but failed to win the title.

Around this point, Guerrero developed an addiction to pain medication stemming from his 1999 car accident and in May 2001 was sent to rehab, missing the entire Invasion storyline that featured his former fellow WCW (and later ECW) wrestlers.

[70][72] On March 1, he defeated the champion CM Punk and Rey Mysterio in a Triple Threat match for the IWA Mid-South Heavyweight Championship.

[86][87] In contrast to a previous WCW storyline with his nephew, Chavo fully agreed with his uncle as their slogan stated: "We lie, we cheat, and we steal, but at least we're honest about it".

To push the new tag team, vignettes were produced, which included things such as the two finagling their way into a rich lady's house and throwing a pool party.

At Survivor Series on November 17, Los Guerreros faced the new champions Edge and Rey Mysterio and the team of Kurt Angle and Chris Benoit for the titles.

[119] At the end of WrestleMania, Guerrero celebrated in the ring with longtime friend Chris Benoit, who had just won the World Heavyweight Championship.

After the match concluded, Guerrero was persuaded to go to hospital by WWE producer Bruce Prichard where his wound was stitched up and he received IV fluids.

[124] On the July 8 episode of SmackDown!, Guerrero pulled a switcharoo with Shannon Moore, who was wrestling as "El Gran Luchadore" and wore the costume.

Guerrero's team consisted of himself, Big Show, John Cena (replacing the originally chosen Rey Mysterio), and Rob Van Dam.

[132][133] Many expected the new champions to defend their title at WrestleMania 21 on April 3, but after encouragement from Chavo,[134][135] Guerrero challenged Mysterio to a one-on-one match instead so they could "bring the house down".

[138] Although the next week they received a rematch to regain the titles, Guerrero abandoned Mysterio, whom he had considered "his family" earlier in the show, costing them the match.

[145] Following his feud with Mysterio, Guerrero was named number one contender to the World Heavyweight Championship and given a title match with Batista.

On the date of his death, a triple threat match between himself, Batista, and Randy Orton was supposed to take place to air on the following episode of SmackDown!

Yet Stephanie McMahon was adamant that Eddie was supposed to win the World Heavyweight Championship, thus starting his second main title reign.

Guerrero was also known for his resourcefulness via other means, such as at WrestleMania XX by rolling up Kurt Angle after loosening his own boot while trapped in the Ankle Lock.

Raw started with all the wrestlers and numerous backstage personnel onstage as Vince McMahon addressed the live crowd, before finishing with a ten-bell salute.

Other wrestlers, primarily Guerrero's nephew Chavo and friends Mysterio and Christian Cage, began paying tribute to him in their matches by using his Frog Splash finisher.