At a glanceHarry Styles's Eros appearance belongs to Eternals. Starfox is another name for Eros, whose relationship to Thanos predates the film in Marvel's comics.
The film behind the headline
The old casting headline refers to Harry Styles appearing as Eros in Eternals. Disney's film reference dates the movie's U.S. release to November 5, 2021, with Chloé Zhao directing. That year matters: rediscovering the character through an older link is different from a studio announcing a new movie appearance.
Marvel also provides an official Starfox feature under the title The Styles of Starfox. It is a useful starting point for the character connection, while the film itself supplies the context for his introduction. Neither a promotional feature nor an old credits scene should be turned into an unsupported promise about a later film.
Source [1] Source [2]Why Eros is also called Starfox
Marvel's character reading guide identifies Starfox as Eros, describes him growing up on Titan alongside his brother Thanos, and traces his comics appearances. It points readers to Iron Man issue 55 for his brief introduction and to Avengers issues 231 and 232 for the beginning of his Avengers chapter and the Starfox name.
Those are comics references. They help explain a character's background, but a screen adaptation does not have to reproduce every comics storyline. Keeping the two versions distinct is especially useful when fan theories combine a film cameo with decades of published continuity.
Source [3]What to check before believing a sequel claim
Look for a named project and a dated studio announcement. A character's existence, a performer's earlier appearance and a confirmed role in a future production are three different claims. An article that establishes only the first two has not established the third.
For more film coverage, the Movies section keeps current headlines separate from these historical explainers. Music coverage is available separately for readers who arrived because of Styles's recording career.
Source [2]