6) Metallo
Metallo, otherwise known as John Corben, is someone that many fans have been calling for to be brought to the screen. It turns out it might have already happened, too, if Man of Steel 2 had been put into production earlier.
Zack Snyder has previously stated that the kryptonite-powered cyborg was to be the main villain of the original MoS 2 before it became Batman V Superman. Subsequently, Metallo’s creator, Professor Emmett Vale, made a cameo in BvS as one of Lex Luthor’s scientists.
Given that overwhelming evidence, Metallo would have been at the top of our list to make an appearance in Man of Steel 2. However, it was recently revealed that the character will be appearing in the next season of Supergirl. Wouldn’t DC keep a hold on the character if they were planning something major for him on the big screen?