The Marvel Cinematic Universe is known for its interconnectivity, with characters making unexpected appearances in various movies.
Notable examples include Robert Downey Jr.'s cameo in The Incredible Hulk and Samuel L. Jackson's recurring appearances throughout the franchise.
Villains have also made surprise returns, such as Samuel Sterns in Captain America: Brave New World 17 years after his last appearance, and Tom Hiddleston's Loki, who has appeared multiple times.
The Marvel Cinematic Universe has always been built around its interconnectivity.
This interconnectivity has raised concerns about the potential return of Ultron, a major Avengers villain.
Ultron's return may ruin the Avengers villain after Marvel's shock reveal.