# Marvel Avengers: Doomsday plot speculation

> Live situation record from CLSTR: https://clstr.news/situations/marvel-avengers-doomsday-plot-speculation
> Updated: 2026-08-22T08:39:17.000Z. Sources: 14. Developments: 2.

Actor David Harbour has triggered significant fan speculation regarding the plot of the upcoming Marvel film ‘Avengers: Doomsday’. During an interview with Variety, Harbour, who plays Alexei Shostakov (Red Guardian), was asked to recite a line of dialogue from the film out of context. He responded in a Russian accent, saying, “You… are Tony Stark.”

This comment has led to various theories concerning Robert Downey Jr., who is set to appear in the film as the villain Doctor Doom. Fans are debating whether the line indicates that Doctor Doom is a multiversal variant of Tony Stark or if the character will use a Stark-like appearance to manipulate the Avengers. While some viewers view the remark as a potential spoiler, others suggest it may have been a joke. Marvel Studios has not officially confirmed the validity of the dialogue.

## Timeline

### 2026-08-22: David Harbour sparks Marvel theories with Avengers: Doomsday comment

David Harbour’s recent comment, ‘You… are Tony Stark!’, has fueled fan theories that Doctor Doom’s identity in ‘Avengers: Doomsday’ may be linked to Tony Stark.

2 sources. https://clstr.news/cluster/david-harbour-sparks-marvel-theories-with-avengers-doomsday-comment

### 2026-08-19: David Harbour sparks Avengers: Doomsday speculation with potential spoiler

David Harbour has sparked Marvel fan speculation after potentially spoiling a major plot point in ‘Avengers: Doomsday’ by reciting the line, “You… are Tony Stark,” during a recent interview.

12 sources. https://clstr.news/cluster/david-harbour-sparks-speculation-over-avengers-doomsday-spoiler

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Cite as: Marvel Avengers: Doomsday plot speculation. CLSTR, https://clstr.news/situations/marvel-avengers-doomsday-plot-speculation