2. Brock Lesnar
MMA fans were extremely displeased when the WWE's "Next Big Thing" invaded their sport in 2007, and even less so by the time he debuted in the UFC in 2008. They felt he was getting fast-tracked (he was) for the sake of money (absolutely). Thing is, Lesnar was actually good - he remains tied for the record for most UFC title defences in the volatile heavyweight division, and holds wins over hall of famer Randy Couture and future hall of famer Frank Mir. He didn't help his case, however, by egging on the fans that were booing him - flipping them the finger after his second fight with Mir, loudly proclaiming that Mir had had a "horseshoe up his ass" and that he'd removed it and beat him with it. His antics also included disrespecting a sponsor and making comments about "getting on his wife" (former WWE Diva Sable) after a match. He was so-so as a coach on The Ultimate Fighter against Junior Dos Santos, showing the Brazilian fighter deserved respect, but also coming down on his team, stating that "you can't make chicken salad out of chicken s**t." Whether it was his brash personality or the fact that he came from pro wrestling, MMA fans hated him so much that they ordered every single event he appeared on, making him the biggest drawing star in UFC history.