Great villains make for great stories in books, in movies and in boxing.
Where would Rocky have been without Apollo Creed? John McClane needed Hans Gruber. Tom Clancy made a living for years writing enormously successful books with Russian villains.
Boxing promoters love the good vs. evil angle. In a less enlightened age, Jack Johnson was cast as evil personified simply because of the color of his skin. Joe Louis vs. Max Schmelling was huge because it became a proxy for a fight against Nazi Germany.
It can be more complicated, though, in boxing. Ali vs. Frazier was a battle where large parts of the population fervently chose sides based on who they believed was the "bad guy." Conservative America hated the now-beloved Ali for his stance against the Vietnam War and for his conversion to Islam. On the other side, fans viewed Joe Frazier as a sell-out.
Who the villain in the fight was depended on your view of what was happening in the world.
All of the boxers on this list have fans. Passionate fans who will be furious that their fighter ended up on a list of villains. Having fans, though, doesn't mean you can't play the villain.