Unlike Thanos (Josh Brolin), the Marvel Cinematic Universe's take on Doctor Doom (Robert Downey Jr.) has had zero buildup ahead of his debut in Avengers: Doomsday. With Avengers: Doomsday less than six month away, Marvel Cinematic Universe head honcho Kevin Feige is defending the lack of buildup for Robert Downey Jr.'s Doctor Doom. Marvel Studios Boss Kevin Feige Defends Lack of Doctor Doom Buildup"I do think that the Thanos buildup has built up in people's heads over the years," Feige told Brandon Davis at San Diego Comic-Con. The entire multiverse arc had originally been built around Kang the Conquerer, who needed to disappear when Marvel Studios cut ties with Jonathan Majors in 2023. Robert Downey Jr. appears as Doctor Doom in Marvel Studios' Avengers: Doomsday.