He is best known for being the strategic leader of the original and legendary Four Horsemen that consisted of Nature Boy Ric Flair, Tully Blanchard, and Arn and Ole Anderson. He is most remembered as a manager in pro wrestling. He guided many wrestlers to singles and tag titles in the NWA. In the early 1990s Dillon served as a front office executive for the WWF before returning to a similar, albeit on-camera role with WCW.

James J. Dillon was born Jim Morrison on June 26, 1942 in Trenton, New Jersey. He started in professional wrestling in 1971 as a wrestler. He wrestled primarily in the Florida area and won a few titles but never rose above mid-card status. He was a good talker, so he quit wrestling and became a manager.

He came to prominence in the NWA's Jim Crockett Promotions. He was a heel manager who always interfered in his matches to help get them the cheap victory. Some of his earlier protege's were Ron Bass, Black Bart, Thunderfoot, "Nature Boy" Buddy Landel, Kendo Nagasaki, Big John Studd, Jimmy Garvin and the One Man Gang.

In late 1985, Dillon was switched to managing Tully Blanchard. It was a move upward as Blanchard was the NWA United States Champion at the time and one of the major heels of the promotion. They did an angle where Tully and JJ, as he was called, kicked Baby Doll out of their little group, which got them even more heat as heels. They also started to hang out with Ric Flair and his "cousins", Ole and Arn Anderson. They "broke" Dusty Rhodes' leg and were soon called the Four Horsemen. They won most of the titles in the NWA and pretty much ran over everybody for the next couple of years.

In 1987, Dillon acquired Lex Luger as an "associate" member of the Four Horsemen. Soon, they pushed Ole out and Luger was made a full member. Dillon was involved in the first "War Games" match with the Four Horsemen against the Road Warriors, Paul Ellering, Nikita Koloff and Rhodes. He ended up submitting in the match due to an injured shoulder, a shoulder that he really dislocated when he landed wrong after a Road Warriors double team.

In 1988, Dillon wrestled a few bullrope matches against the Midnight Rider, who was Rhodes under a mask.

Luger left to be replaced by Barry Windham in 1988, and most wrestling insiders thought this incarnation was the best technical wrestling group of the Four Horsemen. It only lasted four months as Arn and Blanchard left for the WWF in August. Dillon attempted to build the Horsemen back to full strength. He hired Butch Reed as his thug and even got Barry's brother Kendall Windham to join, but they were never called the Horsemen because Dillon was let go shortly after that.To explain Dillon's sudden disappearance, Flair said on TV that he fired him because he let Ricky Steamboat sneak back into the NWA.

Dillon went on to a front office job in the WWF. He later came back to WCW in the mid 1990's and would occasionally appear on TV. He was one of the people begging Arn Anderson to reform the Horsemen in 1998 and was out there with the other Horsemen when Ric Flair returned and they reformed in October of that year.

Dillon retired from the business only to return briefly in 2002 to TNA as the Commissioner. He also had a short run in 2004 for Major League Wrestling managing the Xtreme Horsemen, C.W. Anderson, Simon Diamond, Steve Corino and Justin Credible. He can still occasionally be found managing Tully Blanchard on the Carolina Indy circuit in 2005.

In February of 2006, Dillon made an appearance as a manager at the Chikara Tag World Grand Prix, a 32 team, Tag Team tournament held over 3 days, culminating in the final night at the New Alhambra Arena in Philadelphia, Pennsylvania.