Robert Downey Jr is official as Marvel’s Doctor Doom — everything you need to know

In one move at Hall H of San Diego Comic-Con, Marvel tied the future of the entire MCU to one man. But not just any man. They bet everything on the same man that made Marvel what it is today.

On July 27, Marvel finally revealed the name of the previously untitled "Avengers 5." It would be called "Avengers: Doomsday." As soon as that title was announced, everyone knew what was coming next: the reveal of who would play Doctor Doom in the Marvel Cinematic Universe.

Even if the Russo Brothers — who moments before had been announced by Kevin Feige as the directors of the newly rebranded fifth Avengers movie — weren't surrounded by an army of masked Dooms, it was clear from the title alone that Marvel's greatest villain was finally back. But nobody could have expected what would happen next. That Marvel would announce that Robert Downey Jr. would be returning to the MCU ... as Victor von Doom.

Who is Victor von Doom/Doctor Doom and why does he matter?

Victor von Doom aka Doctor Doom, is arguably the greatest villain in Marvel Comics history. The primary villain of the Fantastic Four, Doom is a powerful sorcerer (like Doctor Strange), a brilliant intellect and the ruler of the fictional Eastern European nation of Latveria. His word is his bond and his goal is to bring peace and prosperity to humankind ... by trying to take over the world.

Like with any character in Marvel comics, Doom has some variance depending on which comic book series he's in. There's Neil Gaiman's Count Otto von Doom, the multiverse conquering Doom Supreme, the Marvel Ultimate universe's Victor van Damme and many others.

I'd expect that Robert Downey Jr.'s version of the iconic villain will have its unique attributes, quirks, etc. However, I'd expect him to still be brilliant, a powerful practitioner of the mystic arts and likely the ruler of the fictional Latveria ... though I'm less convinced on that last part given that Latveria has yet to be introduced to the MCU.

There is a version of Doom though, that I expect Marvel to draw from for Downey Jr.'s upcoming portrayal of the character. In the 2015 "Secret Wars" — expected to heavily influence the sixth Avengers movie "Avengers: Secret Wars" — Doom takes the powers of a group called the Beyonders and uses them to create Battleworld from the remnants of the destroyed Marvel multiverse. This is the most powerful version of Doom in the comics and one I expect Marvel to borrow from heavily.

While there are versions of Doom that are Tony Stark, such as Iron Maniac, or the "infamous Iron Man" series where Doom becomes Iron Man while Stark is in a coma, I don't think these will be the versions Marvel pulls from. Joe Russo explicitly introduced RDJ as "Victor von Doom," so don't expect this Doom to be a Stark variant.

Marvel is now forever tied to Robert Downey Jr.

The second Downey Jr. removed his Doctor Doom mask and donned his iconic Iron Man shades, Marvel had created what's referred to in its cinematic universe as a cannon event. It is, from now on, forever tied to this decision.

The other Marvel movies shown off at SDCC were rendered irrelevant in an instant. " Captain America: Brave New World ," "Thunderbolts," "Blade," " The Fantastic Four: First Steps " and even the recently released " Deadpool & Wolverine " no longer matter. Even if they're as middling as recent Marvel fare, everyone is going to go watch RDJ's return to the MCU.

Which, is exactly what Marvel wants and frankly, what they needed. They had a big problem on their hands with Jonathan Majors being fired as Kang the Conqueror. Marvel had put its eggs in the Kang basket and once those eggs were broken they had to not only salvage multiple movies but to find a new Thanos-level villain for the MCU.

That left Marvel with few options. Picking Downey Jr. to play Doctor Doom, while easy to see as cynical, might have been the best one. There's no villain bigger or more desired by Marvel fans than Doom and Downey Jr., isn't only the biggest MCU star of all time but a recent Oscar winner. If he hadn't been in the MCU already, he's who Marvel would target for the role anyway.

Now, Marvel's only problem is that it doesn't matter if the upcoming slate of Marvel shows and movies is good. They can be masterpieces but if "Doomsday" and "Secret Wars" aren't the best Marvel movies since "Avengers: Endgame," Marvel will be slammed for bringing back Downey Jr. to the MCU, regardless of whether his performance is good or not. They will be accused of being creatively bankrupt and it will force a complete teardown of everything Kevin Feige is built. Hopefully, for him and Marvel, this is the one timeline where they win.

More from Tom's Guide

• 'House of the Dragon’ season 2 finale trailer teases an epic final episode
• New on Netflix: 5 movies and shows to watch this week (July 29-Aug 4)
• 'The Sandman' season 2 — everything we know so far