Tom Holland was one of the first to know about Robert Downey Jr.'s Doctor Doom casting but says it was a "tough secret to sit on" because he has a "reputation for ruining things"

Spider-Man actor Tom Holland was one of the first to know about Robert Downey Jr.'s shock return to the MCU as Doctor Doom – and he admits it wasn't always the easiest thing to stay tight-lipped about.

"I've been speaking to [Robert Downey Jr.] a lot, especially about him making his [Marvel] return, which is super exciting," Holland said on the Rich Roll podcast.

Holland added, "That was a tough secret to sit on because I have a reputation for ruining things. Strategically, I have done no press."

Of course, Holland is known to be somewhat of a magnet for spoilers, with the Spider-Man actor revealing major plot points from Infinity War and Endgame months before release. This one, mercifully, is one he managed to keep to himself.

Robert Downey Jr. made his shock return to the MCU during San Diego Comic-Con's Marvel panel. There, he announced he would not be playing Tony Stark but, instead, would portray villain Doctor Doom in Avengers: Doomsday and Avengers: Secret Wars. 

The former Iron Man actor (that still hurts) will be joined in the pair of Avengers films by a wide-ranging group of heroes which so far include some of the cast of Thunderbolts* and Fantastic Four.

According to a recent report from Variety, Downey Jr. would only return to the MCU on the condition that the Russos brothers – who also directed Avengers: Infinity War and Avengers: Endgame – would return to helm the new Avengers movies. There has also been speculation that the character will first make its debut during 2025's Fantastic Four, though that remains to be seen. Either way: Doom is coming.

For more, check out our guides to upcoming Marvel movies and how to watch the Marvel movies in order. Then check out the latest on Marvel Phase 5 and Marvel Phase 6.