At San Diego Comic-Con on Saturday, Robert Downey Jr. shocked fans by announcing he would return to the Marvel Cinematic Universe. During the Hall H panel, he took off a mask to reveal he would play Doctor Doom, a well-known Marvel villain. Fans had been watching figures in similar masks, making Downey Jr.’s surprise even more exciting. He talked about how much he enjoys playing complex characters, which thrilled the audience. The Russo Brothers, who have directed Marvel films before, will direct the new movies “Avengers: Doomsday” and “Avengers: Secret Wars.” They said they are still focused on making great movies, even with Downey Jr. taking on a new role. Another big news was the introduction of Galactus, a powerful cosmic villain, in “The Fantastic Four: First Steps,” directed by Matt Shakman. The panel also had a fun performance with actors dressed as Deadpool to celebrate the success of “Deadpool and Wolverine,” which became the highest-grossing R-rated movie. Anthony Mackie talked about his role as Captain America in “Captain America: Brave New World,” and Harrison Ford and David Harbour made fun appearances. The Comic-Con panel was full of exciting updates and fun moments for Marvel fans.