Robert Downey Jr. Says Captain America and Doctor Strange Were the MCU’s Toughest Roles to Nail

The Marvel Cinematic Universe has introduced dozens of heroes over the years, but according to Robert Downey Jr., two of them came with a much bigger challenge than most fans may realize.

Downey helped launch the MCU with Iron Manback in 2008, a movie that took a huge risk by kicking off what would become the biggest shared cinematic universe in Hollywood.

Now, as he prepares to return to Marvel as Doctor Doom in Avengers: Doomsday, the Oscar-winning actor is looking back at the performances that impressed him the most.

During an interview with CBR, Downey singled outChris Evans and Benedict Cumberbatch, explaining why he believes they had the hardest jobs when bringing their Marvel heroes to life.

He said: “I still feel like the two hardest characters to pull off was what [Chris] Evans did with Cap. And then, I think, [Benedict] Cumberbatch with Strange was like, ‘Are they really going to?’ Because in the comics, it works. And they were holding these spaces of credibility in the real world, and credibility in the world of magic and sorcery.”

On the surface, Captain America seems like a character who could have come across as overly earnest or old-fashioned. Steve Rogers is the ultimate good guy, and making someone that sincere feel authentic is no easy task.

Evans managed to turn Cap into the emotional center of the MCU, giving audiences a hero whose integrity never felt forced. By the time Avengers: Endgame wrapped up his story, Steve Rogers had become one of Marvel's most beloved characters.

Doctor Strange presented an entirely different challenge. When Doctor Strange arrived in 2016, Marvel was asking audiences to embrace mysticism, alternate dimensions, spellcasting, and reality-bending visuals in a universe that had largely been grounded in science fiction and advanced technology.

It was a major shift for the franchise, and Cumberbatch had to make Stephen Strange believable while guiding viewers into that magical side of the MCU. His performance balanced arrogance, humor, vulnerability, and the increasingly bizarre world around him, helping establish magic as a cornerstone of Marvel's storytelling.

Downey's comments also come at an interesting time. While Marvel has remained secretive about the plot of Avengers: Doomsday, both Evans and Cumberbatch are expected to reprise their MCU roles in the upcoming blockbuster.

Of course, one of the biggest mysteries surrounding the film is how Earth's Mightiest Heroes will react when they come face to face with Doctor Doom, especially since he'll share the same face as their fallen teammate, Tony Stark.

Marvel has yet to explain exactly how that connection works, but it's already one of the biggest questions fans have heading into the next Avengers event.