While in the WWF, Nash was part of The Kliq, an influential backstage group that included Shawn Michaels, Triple H, Scott Hall and Sean Waltman.

Nash left the WWF and returned to WCW in 1996, where he performed under his real name, partnering with Hall as the Outsiders and founding the New World Order (nWo) with Hulk Hogan.

[6] He was initially partnered with Master Blaster Iron, with whom he made his debut at the Clash of the Champions XII on September 5, 1990, defeating Brad Armstrong and Tim Horner.

Nash wrestled as Oz throughout the remainder of 1991 and went on a lengthy losing streak, suffering defeats by Kazmaier, Rick Steiner, Dustin Rhodes, and Arachnaman.

[21] On January 21, 1992, at Clash of the Champions XVIII, he was repackaged as Vinnie Vegas, a wisecracking pseudo-mobster based on Steve Martin's character in the 1990 film My Blue Heaven.

[22] Vegas was quickly recruited into "A Half-Ton of Holy Hell", a stable of large wrestlers created by Harley Race which included WCW World Champion Lex Luger, Big Van Vader and Mr. Hughes.

For the role, he grew long hair, taking on the appearance and demeanor of a cocky thug from Detroit, sporting black sunglasses and leather garments.

[8][26] The duo of Diesel and Michaels defeated The Headshrinkers to win the WWF Tag Team Championship on August 28, making Nash a double champion.

Michaels was irate about his former bodyguard having beaten him to the WWF Championship and was sufficiently motivated to win the Royal Rumble match later that evening, earning himself a title shot at WrestleMania XI.

On September 24 at In Your House 3 in Saginaw, Michigan, Diesel and Michaels challenged the reigning WWF Tag Team Champions Owen Hart and Yokozuna.

In the course of the match, Hart arrived at ringside, entered the ring and was pinned by Diesel for the win and the title, making him and Michaels holders of all three major WWF championships.

At In Your House 6 on February 18, Diesel attempted to regain the WWF Championship from Hart in a steel cage match, losing after The Undertaker attacked him in retaliation for his actions at the Royal Rumble.

[29] After the match, Diesel, Michaels, Razor Ramon, and Hunter Hearst Helmsley, a group of off-screen friends known collectively as "The Kliq", hugged one another in the ring and wished each other farewell.

At Bash at the Beach, Hall and Nash fought the team of Lex Luger, Sting, and Randy Savage and promised to add one more man to their entourage.

In November 1998, Nash and Diamond Dallas Page became a part of a loosely organised "creative team" which also included Dusty Rhodes and Kevin Sullivan.

Nash survived to the end after literally clearing his ring out and big booting Lex Luger, who had Scott Hall in the Torture Rack, over the top rope, and earned his shot at the title.

They feuded with the Perfect Event (Shawn Stasiak and Chuck Palumbo) and won the WCW World Tag Team Championship at Mayhem on November 26, 2000.

Nash lost another "retirement" match to Scott Steiner at SuperBrawl Revenge,[8] but it would not be long before WCW announced the sale of the company to the World Wrestling Federation.

In the course of the evening, the nWo delivered an interview in which they claimed to have reformed, gave a six pack of beer to Stone Cold Steve Austin (which he refused), and traded insults with The Rock.

Following Backlash, Nash was granted a shot at Triple H's World Heavyweight Championship, and the two squared off at Judgment Day on May 18 with Michaels and Flair in their respective corners.

At Bound for Glory, a battle royal was held to determine the number one contender; Rhino won and then defeated Jarrett for the NWA World Heavyweight Championship.

Nash returned to TNA once more on the April 27, 2006 episode of Impact!, announcing in a pre-taped segment that he would give a private interview to Alex Shelley one week later.

He then began managing The Motor City Machine Guns, but this was short-lived before he next appeared in the role of Dr. Nash, psychiatrist and adviser to Kurt and Karen Angle.

On the October 23 episode of Impact!, he formally joined Sting, Booker T, Scott Steiner, and Kurt Angle to create a villainous stable called The Main Event Mafia.

He explained that he never forgave Joe for his scathing comments directed at his best friend Scott Hall's no-show almost a year prior, and befriending him was all part of a long-term plan to screw him out of the title.

[45] At Final Resolution on December 20, Nash took part in the "Feast or Fired" match and won the briefcase containing a shot at the TNA World Tag Team Championship.

[84] Nash, no longer billed as Diesel, returned at SummerSlam in August, attacking CM Punk after he became WWE Champion, which allowed Alberto Del Rio to cash in his Money in the Bank briefcase and win the title, thus turning heel.

[91] On the January 19, 2015 episode of Raw, Nash appeared with X-Pac and Scott Hall to reunite the nWo, and along with The Acolytes Protection Agency and The New Age Outlaws, they beat down The Ascension, who had been insulting legends from past weeks.

On March 29, Nash appeared at WrestleMania 31 alongside Hulk Hogan and Scott Hall, in their attempt to even the odds in favor of Sting in his match against Triple H, who had D-Generation X (Billy Gunn, Road Dogg, Shawn Michaels, and X-Pac) in his corner.

[120] Veteran wrestler "Macho Man" Randy Savage credited Nash[121] for spearheading the nWo Wolfpac faction in 1998 which grew in popularity with the fans and became the company's hottest selling merchandise.