The actor announced his return to Marvel’s superhero movie franchise five years after ending his long run as Iron Man.

Robert Downey Jr. at the Marvel Studios panel at Comic-Con in San Diego on Saturday.

Robert Downey Jr. is going from superhero to supervillain.

The actor, who entertained audiences as Iron Man for more than a decade in several Hollywood blockbusters, is returning to the Marvel cinematic universe as the villain Victor von Doom in two upcoming movies.

“New mask, same task,” Downey announced at a Comic-Con event in San Diego on Saturday, after he unveiled the character’s signature silver mask and green cloak to the roar of a cheering crowd.

“What can I tell you?” he said. “I like playing complicated characters.”

Downey is set to appear as the character, simply known as Dr. Doom, in “Avengers: Doomsday,” which is expected to be released in May 2026, and “Avengers: Secret Wars” a year later.

Downey, 59, has been a prolific actor since the 1980s, portraying characters both serious and comedic.

He received Academy Award nominations for his portrayal of the actor Charlie Chaplin in the 1992 film “Chaplin,” and for his role in the 2008 war comedy “Tropic Thunder.”

After multiple probation violations stemming from an arrest on drug and weapons charges, he was sentenced to prison in 1999 and overcame a long battle with substance abuse.

This year, he won the Academy Award for best supporting actor for his role in “Oppenheimer,” Christopher Nolan’s film about the making of the atomic bomb during World War II. Downey played the titular character’s political rival, Lewis Strauss.

But audiences best know him for helping to start an era of blockbuster superhero movies that began in 2008 with the first “Iron Man” movie.

He played the charismatic genius-inventor-billionaire-arms dealer Tony Stark, who becomes Iron Man and eventually leads a team of heroes, the Avengers, who protect the world against dark forces.

He played the character in sequels and spinoffs including “Iron Man 2,” “Captain America: Civil War” and “Spider-Man: Homecoming.” He last appeared as Iron Man in the 2019 film, “Avengers: Endgame,” in which the character was killed off.

And now Downey is going back to the popular superhero realm with Dr. Doom, a megalomaniacal villainous tycoon from the Marvel comic book series “Fantastic Four,” which was created by Stan Lee and Jack Kirby in 1961.

In the series, Dr. Doom wore a threatening silver mask to hide his scarred face.

The character was previously played by Julian McMahon in the 2005 film “Fantastic Four” and in the 2007 sequel “Fantastic Four: Rise of the Silver Surfer.” A reboot in 2015 featured the actor Toby Kebbell as Dr. Doom.

The casting news comes as Marvel Studios, which has been trying to reverse recent box office misses, brought back two of its most popular characters, Deadpool and Wolverine, with the movie “Deadpool & Wolverine.”

The movie was expected to sell roughly $205 million in tickets in the United States and Canada over the weekend, box office analysts said on Saturday.