About a month ago I put it forth that evidence of Superman wearing a black suit in the Justice League movie might have been revealed through a description for the Justice League movie Multiverse 6-inch action figures as a description implies there may be another costume besides the Superman red and blue.
Now further evidence that Henry Cavill may be wearing a black Superman costume in Justice League comes from an image of a Superman action figure wearing the black suit, which a Redditor posted online:
While the Superman black suit action figure may just be for the toy line, we do see that all the figures shown do match with what is known about the Justice League movie, so it is entirely possible the Superman black suit figure is a part of the movie as well.
In the comic books, Superman dies at the hands of Doomsday and returns wearing a black suit, which could be what they are doing with Henry Cavill and Superman for the Justice League movie.
There have also been rumors and speculation that Superman returns as a bad guy or an evil version of himself, perhaps under the influence of Steppenwolf. The defunct 2008 Justice League Mortal movie actually had a Superman being brainwashed by Maxwell Lord who was bad and who fought and hurt Wonder Woman.
Henry Cavill also teased the Superman black suit a year ago on Instagram:
Justice League has a November 17, 2017 release directed by Zack Snyder, with the story by Chris Terrio and Zack Snyder, the screenplay by Chris Terrio and Joss Whedon, and stars Ben Affleck as Batman, Henry Cavill as Superman, Gal Gadot as Wonder Woman, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, J.K. Simmons as Commissioner Gordon and Willem Dafoe an Atlantean, Nuidis Vulko.
Fueled by his restored faith in humanity and inspired by Superman’s selfless act, Bruce Wayne enlists the help of his newfound ally, Diana Prince, to face an even greater enemy. Together, Batman and Wonder Woman work quickly to find and recruit a team of metahumans to stand against this newly awakened threat. But despite the formation of this unprecedented league of heroes—Batman, Wonder Woman, Aquaman, Cyborg and The Flash—it may already be too late to save the planet from an assault of catastrophic proportions.