Doctor Doom Walks Into the Baxter Building in Fantastic Four: First Steps — Here Is What It Means for Avengers: Doomsday

Fantastic Four: First Steps closes with a mid-credits scene that places Doctor Doom inside the Baxter Building apartment of Reed and Sue Richards — four years after the film's events conclude — approaching their super-powered child, Franklin Richards, according to Polygon. The sequence does not show Doom's face but establishes him as wearing a green cape and holding his mask, and sets up a direct pathway for the Fantastic Four to cross into the main MCU ahead of Avengers: Doomsday in 2026.

The Details

Fantastic Four: First Steps is set in Earth-828, a parallel universe separate from the main MCU, which occupies Earth-616 (also designated Earth-199999), according to Inverse. The mid-credits scene does not take place at the film's conclusion — it is positioned four years after those events, per Polygon, signaling a meaningful time jump before the Fantastic Four's expected debut in the wider MCU.

Doctor Doom's arrival at the Baxter Building centers on Franklin Richards, the young son of Reed Richards and Sue Storm. Polygon reported that Doom appears to be targeting Franklin specifically, and that Franklin's Power Cosmic — an extraordinarily potent energy source — appears to be the object of interest. The nature of Doom's intentions is not stated explicitly in the scene.

The figure's face remains obscured throughout the sequence. Inverse noted that the character is "presumably" the Robert Downey Jr. portrayal of Doctor Doom, the actor who is rumored to take on the role in Avengers: Doomsday. That connection carries medium confidence at this stage; no official casting confirmation has been issued.

Earlier in the film, a subtle setup for Doom's presence appears during a United Nations address by Sue Richards. A placard for the nation of Latveria — Doctor Doom's home country in Marvel Comics — is visible in the assembly hall, according to Inverse. The placement functions as a narrative breadcrumb before the mid-credits reveal.

The mid-credits scene, as Polygon described it, positions the Fantastic Four squarely in the orbit of Avengers: Doomsday. "Doom has crept into the Richards' Baxter Building apartment," Polygon wrote. "What he intends to do next, and how that bridges Avengers: Doomsday, is the big unknown."

Context

The groundwork for the Fantastic Four's transition from Earth-828 to Earth-616 was laid before First Steps even reached theaters. The post-credits scene of Thunderbolts* — Marvel's earlier 2026 release — showed the Fantastic Four's ship entering Earth-616's airspace, according to Polygon, signaling the crossover to MCU audiences ahead of the First Steps premiere. The First Steps mid-credits scene now provides the in-universe motivation for that journey.

The Fantastic Four hold a particular place in Marvel Comics history: the team was the first superhero group created by Stan Lee and Jack Kirby, debuting in 1961, according to Hero Haven. The characters' MCU debut has been anticipated for years following the completion of Disney's acquisition of 20th Century Fox, which previously held the film rights.

Doctor Doom is one of the most prominent villains in Marvel Comics history and has long been associated with the Fantastic Four in the source material. His arrival in the MCU — and the apparent targeting of Franklin Richards — places the Fantastic Four at the center of the Avengers: Doomsday narrative architecture, not on its periphery.

What's Next

Avengers: Doomsday is scheduled for release in 2026. The mid-credits scene of First Steps establishes that the Fantastic Four will be active participants in that film, with Doom's interest in Franklin Richards likely to drive a significant portion of the story. Polygon identified the Doom-Franklin dynamic as "the big unknown" in terms of how the storyline bridges to Doomsday.

The question of Robert Downey Jr.'s involvement as Doctor Doom remains unconfirmed by Marvel Studios. Inverse noted that the scene deliberately withholds Doom's face, consistent with how Marvel typically handles major casting reveals ahead of official announcements.