The Marvel Studios president told Empire that the alien race known as the Skrulls will not appear in the film, despite reports to the contrary.
However, Feige did confirm that Avengers will see the Captain America-led team take on an "alien" threat with roots in Marvel's comic book universe.
"It's not Skrulls, I've been clear about that," he said. "Beyond that, we want to hide it. The identity of the alien race is not impactful. It exists in the comic books, but we're not setting up the Kree-Skrull war or anything like that."
Feige went on to debunk speculation about the Red Skull's involvement in the movie, but refused to rule out the villain's return in a later entry in the series.
"Was Skull vaporised at the end of the movie, or thrust into another realm?" he added. "That remains to be seen. It would be fun to see Skull in future, but he's not in this one."
The Avengers, directed by Joss Whedon, arrives in theatres on April 27 in the UK and on May 4 in the US.
Watch a trailer for The Avengers below: