5. Bloodsport
There have been a number of Superman villains named Bloodsport but, in this instance, we'll be focusing on the first one; Robert DuBois (rather than, for example, the fanatical racist/white supremacist Alex Trent). DuBois suffers a mental breakdown after having become obsessed with the Vietnam War, then learning that his brother Michael ('Micky') had gone to fight in his place and became a quadruple amputee whilst out there. A man representing Lex Luthor then persuades the very angry DuBois that Superman is his enemy and arms him with super-powered technology, including a teleporting device and bullets made out of Superman's weakness - Kryptonite. This version of Bloodsport is a viable option given that he's essentially working for Lex Luthor, whom we already know exists in the
Man of Steel universe (thanks to all those LuthorCorp Easter eggs), and could represent the physical threat to compliment Luthor's intellectual threat.