Duncan Crabtree-Ireland, the executive director and chief negotiator for the actors’ union, has spent the past two decades toiling behind the scenes during contract talks. The spotlight, he knows, is for the SAG-AFTRA president, usually a well-known performer like the current office holder, Fran Drescher.

But ever since the guild went on strike on July 14 for the first time in 40 years, things have been different.

In the past three months, Mr. Crabtree-Ireland, 51, has stepped out from behind the negotiating table and made fiery speeches, walked film festival red carpets and reached out to the union’s younger members via Instagram reels. His more frequent appearances have given people ample opportunity to see the tattoos on his forearms, a visual clue to how much the professional and the personal are intertwined for him. On the right are five symbols — a record, a play button, a film reel, a megaphone and a radio antenna — representing the contracts he’s negotiated for union members in the music, film/TV, radio, commercial, video and broadcast industries. On his left arm is a coil with five loops that represent the five children he has adopted with his husband, John.

“It’s not just a job for me,” he said in an interview. “This is where I’ve spent the vast majority of my professional career, and I really care about what happens to our members.”

Now, however, Mr. Crabtree-Ireland is facing his most challenging public moment. Come Monday, when the union returns to the negotiating table with the studios in an attempt to resolve the strike that has much of Hollywood at a standstill, all eyes will be on him.

(Ted Sarandos, a co-chairman of Netflix; David Zaslav, the chief executive of Warner Bros. Discovery; Donna Langley, the chief content officer of Universal Pictures; and Robert A. Iger, Disney’s chief executive will also be in attendance, along with the chief negotiator for the studios, Carol Lombardini.)

When the Writers Guild of America agreed to a tentative deal for its 11,500 members last Sunday, that left SAG-AFTRA as the lone union holding out for a new deal. How this week’s negotiations go will therefore affect not just the tens of thousands of people in Mr. Crabtree-Ireland’s guild, but everyone in the entertainment industry.

The dual strikes have been devastating financially, with more than 100,000 behind-the- scenes workers like location scouts, makeup artists and lighting technicians out of work. The California economy has lost an estimated $5 billion. Major studios like Disney, Warner Bros. Discovery and Paramount Global have seen their stock prices drop. Analysts have estimated that the global box office will lose as much as $1.6 billion in ticket sales because of movies whose releases were pushed back to next year.

“I’m 100 percent sure that he’s a deal maker, a realist and that he understands the horse trade,” Bryan Lourd, chief executive of Creative Artists Agency, said of Mr. Crabtree-Ireland. “He has the list of what he’s got to get and what he can lose.”

Mr. Crabtree-Ireland said that he was encouraged by the tentative deal reached by the writers and that he was anxious to get a deal done for the actors. But he added that he did not feel pressure because the actors were the only ones on strike. The push he feels, he said, was “because of the economic impact and the impact on our members and others.”

The negotiations on Monday will be the first time that the union and the Alliance of Motion Picture and Television Producers, which bargains on behalf of the studios, have talked since the actors went on strike. At the time SAG-AFTRA walked out, the dialogue between the sides had reached a boiling point.

Mr. Iger, of Disney, elicited the ire of many writers and actors by saying that those on strike were not being “realistic” in their demands. Ms. Drescher responded by saying Disney should put Mr. Iger “behind doors and never let him talk to anybody” and compared him and the other studio chiefs to “land barons of a medieval time.”

Mr. Crabtree-Ireland was traditionally seen as a voice of reason by several studio executives, but at a news conference on July 13 announcing the strike, he appeared beside Ms. Drescher and spoke passionately about the studios’ intentions to replace background actors with artificial intelligence technology in perpetuity.

The studios issued a statement, arguing that A.I. agreements could only be made for a specific project — but by then, A.I. had become a rallying cry for striking actors. The actors, like the writers, have also said that the streaming era has worsened their compensation and overall working conditions.

Mr. Crabtree-Ireland played down the volatile nature of the rhetoric in the interview, and said Ms. Drescher’s comments about Mr. Iger were just a response to a statement that had angered “a very wide swath of our members.”

“She was elected by the members to do this job,” he added. “So I feel very confident walking into a room with Fran and the rest of our negotiating team who have had extraordinary unity throughout this entire process.”

The studio alliance declined to comment for this article.

While the writers’ deal would seem to give the actors and studios a blueprint for their negotiations, Mr. Crabtree-Ireland pointed out that SAG-AFTRA has different asks. For instance, he noted the new level of transparency reached between writers and the streaming companies regarding residual payments was “huge.” But the actors are looking to secure a revenue-sharing deal with the studios, a proposal the alliance has deemed a non-starter.

“We really feel that the companies need to share a share of the revenue that’s coming from streaming,” Mr. Crabtree-Ireland said. “And we are not presently considering an approach that doesn’t attach in that way.”

Mr. Crabtree-Ireland joined SAG-AFTRA in 2000, a Georgetown graduate with a law degree from the University of California, Davis, who spent the first two years of his career in the Los Angeles County District Attorney’s Office.

He rose quickly at the union, first to general counsel, then adding chief operating officer to his title. In 2021, he was named national executive director and chief negotiator, a job that pays $989,700 annually.

Outside of the office, Mr. Crabtree-Ireland raises his children ranging in age from 4 to 18 with his husband. The two were first married in 2004, one of the first 100 same-sex couples to wed in San Francisco before the California Supreme Court annulled the unions.

While well-liked by both his colleagues and his adversaries, his performance during the strike has earned some critiques from his own membership. Despite the loyalty exhibited on the picket lines, many who have dealt with the union behind the scenes describe a messy, disorganized approach — specifically when it comes to the rules about what its members can and can’t do during the strike.

One point of contention was the issue of interim agreements, which essentially allowed actors to work on and publicize projects that were not backed by the studios the union was striking against.

The rules were fuzzy, however, and many actors were confused about what was permissible. The comedic actress Sarah Silverman blasted SAG-AFTRA on her Instagram account, and Viola Davis declined to begin production on a film granted an interim agreement. Soon, publicists began hounding the union to clarify whether actors could promote independent films without worrying that they were crossing the picket line.

On Aug. 24, less than a week before the start of the Venice and Telluride Film Festivals, Mr. Crabtree-Ireland issued a statement that read in part, “Whether it’s walking a picket line, working on approved Interim Agreement productions, or maintaining employment on one of our other permissible, non-struck contracts, our members’ support for their union is empowering and inspiring.”

Mr. Crabtree-Ireland also talked to many actors who had concerns.

“I underestimated how quickly our members were going to need that information,” Mr. Crabtree-Ireland said. “That is one of the few things that I would do differently.”

It was a pragmatic response, in keeping with the reputation Mr. Crabtree-Ireland has built throughout his career. And many in the entertainment industry are hoping that same style will be a key in the negotiations that could get Hollywood back to business.

“It’s tricky to navigate because he’s trying to please his members and fight for their issues and a lot of them have different issues,” said Lindsay Dougherty, lead organizer for Teamsters Local 399, the union that represents Hollywood workers like truck drivers, casting directors and animal trainers. “It’s obviously not all on him, but I’m sure he feels the pressure.”

Brooks Barnes contributed reporting.