Ian McKellen walked up to Anthony Mackie on the set of Avengers: Doomsday and said, "Hello, son." Mackie told the story in an interview with IMDb, and the exchange quickly travelled through The Independent and on to Variety, which reported it on 29 July 2026.

McKellen, reprising his X-Men role as Magneto, asked Mackie what he was doing in the film. "I'm Captain America," Mackie replied. McKellen's response, per Variety: "Wonderful… and you deserve that." Variety

Mackie took over the Captain America mantle from Chris Evans' Steve Rogers in The Falcon and the Winter Soldier and then led Captain America: Brave New World. The Doomsday set was the first time he and McKellen shared a Marvel production — a passing of the torch between two actors whose franchises, the Avengers and the X-Men, had been separated for decades by studio rights.

The film itself is stacked. The Russo Brothers, who directed Avengers: Infinity War and Endgame, are back at the helm. Robert Downey Jr. returns to Marvel — but not as Tony Stark. He plays Doctor Doom, the Latverian dictator and Fantastic Four villain. The confirmed cast also includes Pedro Pascal, Paul Rudd, and Channing Tatum as Gambit. Alongside McKellen, a wave of original X-Men actors are back: Patrick Stewart, James Marsden, Kelsey Grammer, Alan Cumming, and Rebecca Romijn. Marvel confirmed the cast during a five-and-a-half-hour live stream in March 2025. The Independent, 18 April 2025

McKellen also shared a lighter behind-the-scenes detail from the production. Speaking at a Rome film festival, he said the Russo Brothers told him to "look more furious" during an action scene involving Magneto's magnetic powers. To find the rage, McKellen said he pictured destroying Donald Trump's Mar-a-Lago resort. Variety

For fans, the McKellen-Mackie moment captures something the cast lists alone can't convey: the human texture of a set where veteran Shakespearean actors and blockbuster regulars are working side by side on a film that merges two of Marvel's biggest franchises. Whether the film delivers on that scale is a question for December.

Avengers: Doomsday is scheduled to reach theatres on 18 December 2026.