https://cdnph.upi.com/ph/st/th/2631784554266/2026/upi/677959408bc43f0786b26ae44c1142dd/v1.5/Avengers-Doomsday-trailer-Robert-Downey-Jr-appears-as-Doctor-Doom.jpg" /> The "Avengers: Doomsday" trailer brings together superheroes from multiple Marvel franchises and introduces Robert Downey Jr. as Doctor Doom.