Ideally, multiple athletes would fill that role, the way elite quarterbacks like Tom Brady, Aaron Rodgers and Russell Wilson all function as N.F.L. standard bearers. But while McGregor was inactive, the U.F.C. did not always have a single, standout, crossover star.
The former bantamweight champion Ronda Rousey played that role in the mid-2010s, but she has not fought since 2016, after back-to-back losses, and she has not publicly expressed interest in returning.
Her predecessor, the longtime welterweight champion Georges St-Pierre, took a four-year hiatus starting in 2013 and ending with a November 2017 win over Mike Bisping. Last year, St-Pierre, a Canadian, retired for good.
The light-heavyweight champion Jon Jones, who currently tops the U.F.C.’s pound-for-pound rankings, rode a string of spectacular wins to stardom in the early 2010s. But arrests and three failed tests for performance-enhancing drugs have sidelined him for long stretches, limiting his profile.
McGregor is unambiguously famous, however, and in a sport where pay is proportional to the size of the audience a fighter draws, a star at the top of the roster has other U.F.C. fighters envisioning their own paydays.
Jorge Masvidal, a welterweight contender who beat Nate Diaz in a November fight at Madison Square Garden that was attended by President Trump, is in line for a fight with the champion Kamaru Usman. But Masvidal told reporters on Thursday that he would rather fight McGregor, framing the choice as a business decision.
“If me and Conor go in the octagon, what happens? It’s one of the biggest fights in history,” Masvidal said. “Just by math, proven by what Conor’s been doing, the last couple fights that I’ve had — the engagement, the pay-per-views.”