Injustice 2 had a large cast out of the gate and even more were added post-release, but the well of DC characters (and even non-DC characters) is deep, so there were plenty of characters that were conceived that didn’t make the cut.
Concept artist Justin Murray, who worked on the game, recently shared art for some of those unused characters as well as art for other aspects of the game. You can find all the art on Murray’s portfolio website right here to see images of Kryto the Superdog, Mr. Freeze, Detective Chimp, Blue Bird, Etrigan, Detective Chimp, and assorted Darkseid monsters for an idea of what those characters would have looked like had they made an appearance.
For more on Injustice 2, you can read our review right here.