The UFC saw two title fights in the month of December as Benson Henderson defended the lightweight belt against Nate Diaz and Cain Velasquez reclaimed the heavyweight championship by dominating Junior dos Santos.
Outside of the world's premier MMA organization, Bellator also crowned a new heavyweight champion. With Cole Konrad retiring, the belt was up for grabs in the heavyweight tournament final featuring Alexander Volkov and Richard Hale.
A year in MMA that had many ups and downs finished strong with its final month. Let's take a look at the fighters who delivered the best performances of December.
Hector Lombard disappointed in his UFC debut against Tim Boetsch, but the former Bellator middleweight champion came back strong in his second Octagon appearance at UFC on FX: Sotiropoulos vs. Pearson.
Against Rousimar Palhares, Lombard came out much more aggressive and was able to finish his Brazilian opponent in the opening round.
While he only boasts a 1-1 UFC record at the moment, Lombard's name value puts him a couple big wins away from a title shot.
Back-to-back losses to Anderson Silva and Tim Boetsch had some believing Yushin Okami was beginning to fade as a fighter. Now, Okami is back in the mix for a middleweight title shot.
In August, Okami righted his ship with a win over Buddy Roberts. That gave him the chance to re-establish himself as an elite 185-pound fighter in a bout against Alan Belcher.
Okami kept the well-rounded Belcher on the defensive for all three rounds of their bout at UFC 155 and walked away with an important decision win.
Costa Philippou stepped in as a replacement for Chris Weidman at UFC 155, where he took on middleweight contender Tim Boetsch.
Despite the short notice, Philippou delivered the biggest win of his career by stopping Boetsch with punches in the third and final round.
With five straight victories, Philippou has emerged as the newest contender in the deepening middleweight division.
Following a loss to Nate Diaz in a bout that could have earned him a lightweight title shot, Jim Miller came back strong in a UFC 155 fight with Joe Lauzon.
Miller bloodied Lauzon with standing elbows early in the bout and continued to punish his opponent for the majority of the three-round fight.
With the win, Miller finds himself back in the hunt for a shot at the lightweight championship.
Considered one of the brightest young fighters in the welterweight division for quite some time, Rory MacDonald was afforded the opportunity to make a statement against a former UFC champion in B.J. Penn.
MacDonald withstood a strong start by Penn and took over the fight once his opponent began to fade. The Canadian left Penn battered and bruised at the end of three rounds and earned himself a decision victory.
By beating Penn soundly, MacDonald has now emerged as a serious contender in the 170-pound division.
Ever since a loss to Phil Davis in April 2010, Alexander Gustafsson has been tearing through his competition.
At UFC on Fox: Henderson vs. Diaz, Gustafsson picked up a sixth straight victory and the biggest one of his young career.
Gustafsson used his reach to gain an edge over Mauricio Rua when standing and surprised many by scoring a number of takedowns en route to a decisive decision win.
With Cole Konrad out of the picture, Alexander Volkov was given a clear path to the Bellator heavyweight title via a tournament that spanned the final months of 2012.
Volkov moved to the semifinals by beating Strikeforce veteran Brett Rogers and advanced further to the finals by stopping former UFC competitor Vinicius Queiroz with punches.
In the tournament finals, which also served as a heavyweight title fight, Volkov was able to stay standing and methodically picked apart Richard Hale to earn the Bellator belt.
At Bellator 83, the relatively unknown Jessica Eye took on one of the top female fighters on the planet in Zoila Gurgel. Bellator's women's strawweight champion, Gurgel had won seven straight fights and was looking to continue her success in the flyweight division against Eye.
Both fighters came out strong, but Eye got the better of the early exchange and wobbled Gurgel. That allowed Eye to press forward and clinch with her opponent, who eventually went to sleep in a standing arm triangle choke.
Right now, Bellator does not have a champion in the women's flyweight division, but Eye is making a strong case to be the favorite whenever the organization holds a tournament for that weight class.
Coming off of two close fights with Frankie Edgar, lightweight champion Benson Henderson was in need of a dominant win to prove he was deserving of the belt around his waist.
Against Nate Diaz, Henderson was able to earn the definitive victory he had been seeking.
The titleholder took Diaz down frequently and even looked better than the challenger on his feet, where many thought he would face the most difficulty heading into the fight.
One year after being knocked out by Junior dos Santos, Cain Velasquez was able to regain the heavyweight title from the Brazilian by looking like a completely different fighter in the rematch.
Velasquez dropped Dos Santos with a right cross in the opening round, and he owned the fight from that point forward.
Dos Santos was drained of his energy and had no answer for the constant pressure from Velasquez, who repeatedly took the fight to the ground and pounded away on his opponent's face.