20. Matt Mitrione
Mitrione is a former UFC heavyweight fighter. However, the promotion suspended him in 2013 after his disgusting comments about Fallon Fox. He insulted the transgender MMA fighter in a despicable way. The UFC claimed that he violated their code of conduct.

Several high-profile figures called out Fox including Joe Rogan. The popular commentator said that she presented a danger to cisgender women. But he made it clear that his criticism wasn’t personal toward Fox. On the other hand, Mitrione made disgraceful comments (via Bleacher Report).