Avengers: Infinity War featured nearly every character who’s appeared in a Marvel Cinematic Universe movie with just a few notable exceptions.
Barton ditched the Hawkeye gimmick in favor of the Ronin costume in the aftermath of Marvel Comics’ version of Civil War.
In that storyline, Ronin was a mysterious warrior who joins the Avengers for a special mission to Japan.
Renner’s Clint Barton is wearing the costume of a Marvel character called Ronin, who was first introduced in the pages of New Avengers #11 by Brian Michael Bendis and David Finch.