10. Bellator, Invicta, World Series of Fighting all showed the MMA landscape is biger than just the UFC -- Though the UFC is the biggest, they're not the only high level MMA promotion. Bellator finished the year out strong as they anticipate a move to Spike in 2013. World Series of Fighting made its debut on NBC Sports, and Invicta's all-female promotion earned respect with two shows this year.
9. Brock Lesnar, Kenny Florian, Mark Hominick and Stephan Bonnar said goodbye to MMA: After losing to Alistair Overeem late in '11, Lesnar hung up his gigantic gloves. Back issues forced Florian to quit fighting, but he still has an active role in the sport as a commentator for FX. Fan favorites Hominick and Bonnar also retired. Bonnar's came after a fight Anderson Silva ended in a loss and a suspension for a banned substance.
8. GSP's return -- UFC welterweight champion Georges St-Pierre tore his ACL in October of '11. He finally returned to the cage in November this year, beating Carlos Condit in a bloody decision.
7. MMA stymied in New York ... again -- Though MMA was legalized in Vermont, the sport remains out-of-bounds in the Empire State. Dreams of a UFC pay-per-view in Madison Square Garden will have to remain dreams for another year as the bill to legalize the sport failed to reach the floor for a vote.
6. Jon Jones arrested for DWI -- In May, UFC light heavyweight champion Jones was arrested after he crashed his Bentley into a pole in Broome County, N.Y. He later pleaded guilty, paid a fine, and had his driver's license suspended. Jones' popularity took a hit with this incident.
5. Suspensions for Alistair Overeem and Nick Diaz: It wasn't a great year for former Strikeforce champs. Overeem was slated to fight Junior dos Santos for the UFC heavyweight championship in May, but was suspended when his testosterone levels were out of whack. Diaz was also suspended when he tested positive for marijuana metabolites.
4. Strikeforce's demise -- The Zuffa-owned, Showtime-aired promotion canceled two shows this fall after injuries hurt their drawing power. Ronda Rousey, their bantamweight champion and one of their biggest draws, was named the UFC champ, and other Strikeforce fighters were given UFC bouts. Finally, the promotion confirmed their January event will be their last.
(Getty)3. UFC cancels an event -- A week and a half before UFC 151, Dan Henderson pulled out of his main event, title fight with Jones. The UFC offered Jones a bout with Chael Sonnen, which Jones turned down. (They will fight in April after coaching on "The Ultimate Fighter.") The UFC decided to cancel UFC 151, making it the first time they had made such a move.
2. Ronda Rousey to the UFC -- It was a pretty good year for the Olympic judo medalist turned fighter. Rousey won the Strikeforce bantamweight championship and defended it, and appeared on the cover of ESPN the Magazine's "Body Issue." But her biggest landmark came late in 2012, when she was named the UFC's first female fighter. She'll defend the UFC's women's bantamweight championship in February.
1. Injuries, injuries, injuries -- As you may have noticed while reading this list, more than anything else, injuries made a mark on the MMA landscape. Time and time again, UFC cards were rewritten as injuries affected champs Jose Aldo, Dominick Cruz, Georges St-Pierre and stars Vitor Belfort, Cung Le, Henderson and Frank Mir, among others. Strikeforce canceled two events because of injuries. Injury announcements became the norm.