UFC 12: Judgement Day was a mixed martial arts event held by the Ultimate Fighting Championship on February 7, 1997 at the Dothan Civic Center in Dothan, Alabama. The event was seen live on pay per view in the United States, and later released on home video.

UFC 12 was the first UFC event to feature weight classes; heavyweights (200 lb and over) and lightweights (199 lb and under) battled in two separate mini tournaments, each consisting of two semifinal bouts and a finals match.

The event also featured a Superfight between Dan Severn and Mark Coleman. The fight would unify the UFC Superfight Championship with the UFC tournament championship and determine the first ever UFC Heavyweight Champion. Mark Coleman was a late substitution for Don Frye, who had earned the rematch with Severn after winning the Ultimate Ultimate 1996, but was unable to participate in UFC 12 because of injuries he had suffered in that previous event. Frye never returned to the UFC. "Judgement Day" also featured two alternate bouts in case of tournament injury.

Matthew John Serra (born June 2, 1974) is an American mixed martial artist and Brazilian Jiu-Jitsu black belt. He is a former UFC Welterweight Champion and an ADCC Submission Wrestling World Championship silver medalist. He began practicing martial arts at an early age, first studying kung fu. In the 1990s, he began studying Brazilian Jiu-Jitsu under Renzo Gracie and on May 23, 2000 he obtained his black belt, the first American to do so under Gracie. He is one of only two people in MMA to defeat Georges St-Pierre, the other being UFC Hall of Famer Matt Hughes.

Serra won first place at the Brazilian Jiu-Jitsu Pan American games in 1999 and won third place at the 1999 World Championships in Brazil as a brown belt. Continuing his Martial Arts career, he competed in the ADCC Submission Wrestling World Championship choking out Takanori Gomi, winning a decision over Jean-Jacques Machado, and placing 2nd in the 66–76 kg division. Serra was invited to compete in Pride 9 against Johil de Oliveira but the bout was called off at the last minute when Oliveira was burned in a pyrotechnics accident backstage. Soon after, Matt began to compete in the UFC organization where he built up a record of four wins and four losses. One of the losses was a close decision fight with future Welter and Lightweight champ B.J. Penn which would have earned him a title shot in the failed Lightweight tournament.

Vítor Vieira Belfort (Portuguese pronunciation: [ˈvitoʁ viˈejɾɐ bɛwˈfɔʁ]; born April 1, 1977) is a Brazilian mixed martial artist and former UFC Light Heavyweight Champion. Belfort was born in Rio de Janeiro and studied jiu-jitsu with the Gracie family, namely Carlson Gracie. He received a black belt under Carlson and currently trains with Xtreme Couture, fighting in the middleweight division. He is currently ranked as the #3 middleweight in the world by MMA Weekly.

Vítor was born on April 1, 1977 in Rio de Janeiro, Brazil to a French father and a Greek mother. Belfort is married to Joana Prado and together they have three children, a son named Davi (born February 5, 2005), a daughter named Victoria (born October 31, 2007), and a daughter named Kyara (born June 7, 2009).

Belfort also had a small part in a reality show on Brazilian television and appeared next to his wife when she was photographed for the Brazilian edition of Playboy.

On January 9, 2004, Vítor's sister, Priscila Belfort disappeared and the relatives received no information about her. In August 2007, a woman (identified as Elaine Paiva) confessed that she participated in her kidnapping and killing and that she was kidnapped to pay off a four thousand dollar debt Paiva had with drug dealers. Paiva was arrested along with three others alleged to be involved in the kidnapping. The group allegedly buried her body in the woods in Rio de Janeiro where police conducted searches but her remains have never been found. Her family however do not accept this version and believe that Priscila is still alive somewhere. Vítor still maintains a missing sign in the Brazilian version of his website.

Wanderlei César da Silva ( /ˈvændərleɪ/ VAN-dər-lay; Portuguese: [vɐ̃dɛɾˈlej ˈsɛzɐr dɐ ˈsiɫvɐ];Japanese: [ba̠nda̠ɽe̞i ɕiü͍βa̠]; born July 3, 1976), nicknamed "The Axe Murderer", is a Brazilian mixed martial artist, who has competed in Japan's Pride Fighting Championships and the American based Ultimate Fighting Championship (UFC). Silva is known for his aggressive fighting style with the majority of his fights ending in knockout or referee stoppage due to strikes. His style includes engaging opponents with punches and knees from the Muay Thai clinch. He holds the record for the most wins and knockouts in Pride FC history. He is currently ranked as #22 best middleweight fighter in the world by FightMatrix.com.

Silva began his training under Rudimar Fedrigo at the Chute Boxe Academy in his hometown of Curitiba, Brazil. Although he specializes in muay Thai, he has also trained and received his black belt in Brazilian jiu-jitsu from trainer Cristiano Marcello. Silva was given the nickname "Cachorro Louco" ("Mad Dog") in Brazil because of his aggressive style and his pre-fight opponent "stare down". He is the former IVC Light heavyweight Champion, former PRIDE Middleweight Champion, and the 2003 PRIDE Middleweight Grand Prix Tournament Winner.

Dana White (born July 28, 1969) is the current President of the Ultimate Fighting Championship (UFC), a mixed martial arts organization based in the United States.

Born in Manchester, Connecticut on July 28, 1969, White grew up in Las Vegas, Nevada, Ware, Massachusetts and Levant, Maine. White is a passionate Boston Red Sox fan. During his youth, he bounced back and forth between Boston and Maine. He attended the University of Massachusetts Boston but did not finish; however, while there he did launch a boxing program for inner-city youth.

White has a background as an aerobics instructor. In 1992, White established Dana White Enterprises in Las Vegas. He conducted aerobics classes at three gyms in the Las Vegas area and began managing MMA fighters Tito Ortiz and Chuck Liddell.

While working as a manager, White learned that Semaphore Entertainment Group, the parent company of the UFC, was looking for a buyer for the UFC. White contacted childhood friend Lorenzo Fertitta, an executive at Station Casinos, and a former commissioner of the Nevada State Athletic Commission. Within a month, Lorenzo and his older brother Frank bought the UFC, with White installed as its president. White currently owns about 9% of Zuffa, LLC, the entity the Fertitta brothers created to own and manage the UFC.