Jake Gyllenhaal received a masterclass in Broadway acting while starring in “Othello.”

The actor, who co-leads the production as Iago alongside Denzel Washington’s title character, told Variety that despite having previously starred in Broadway plays, “Othello” was a whole other feat. It was Washington who helped make Gyllenhaal “calmer” as a stage star, as Gyllenhaal was in a “total panic” about the part.

“I was beginner beyond beginner. I’m not like this usually. I had to spark my brain with other people’s brilliance. I watched everything I possibly could,” Gyllenhaal said, citing how fellow “Othello” alum Ian McKellen gave him a “renewed inspiration” in the role. (McKellen formerly played Iago on the West End.) In total, Gyllenhaal “spent a year working on it.”

Yet even with all of his prep, Gyllenhaal remained “insecure” about his turn onstage in the role.

“I struggled in the first few previews,...