UFC 15: Collision Course was a mixed martial arts event held by the Ultimate Fighting Championship on October 17, 1997, in Bay St. Louis, Mississippi. The event was seen live on pay per view in the United States, and later released on home video.

UFC 15 was headlined by a UFC Heavyweight Championship bout between Maurice Smith and Tank Abbott. Abbott was brought in as a last-minute replacement for Dan Severn, who couldn't fight because of an injured hand.

UFC 15 featured a Superfight between Randy Couture and Vitor Belfort, a Heavyweight Tournament, and two alternate bouts. The show also marked the last event to feature Bruce Beck, who had been the main play-by-play announcer starting with UFC 4. He was replaced by Mike Goldberg in UFC 16. This was the first Pay-per-view UFC event to feature a second referee, Joe Hamilton, who handled the less significant matches while "Big" John McCarthy still handled all the title and championship matches.

Collision Course marked a major change in the UFC's rules, with limitations set on permissible striking areas. Headbutts, groin strikes, strikes to the back of the neck & head, kicks to a downed opponent, small joint manipulation, and hair pulling all became officially illegal.

Year 15 (XV) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Caesar and Flaccus (or, less frequently, year 768 Ab urbe condita). The denomination 15 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Randy Duane Couture (pronounced /koʊˈtʊər/; born June 22, 1963) is an actor, retired American mixed martial artist, collegiate and Greco-Roman wrestler. During his tenures in the Ultimate Fighting Championship (UFC), Couture became a three-time UFC Heavyweight Champion, two-time UFC Light Heavyweight Champion, an Interim UFC Light Heavyweight Champion, and was the UFC 13 Heavyweight Tournament Winner. Couture is the first fighter to hold two UFC championship titles in two different divisions (heavyweight and light heavyweight). Couture has competed in a record 15 title fights. He holds the most title reigns in the UFC with five. His last fight with Lyoto Machida marked his 24th fight in the UFC, the third most amount of fights in the UFC (Tito Ortiz is first with 26 and Matt Hughes is second with 25). Couture is one of the first members of the UFC Hall of Fame. He is the only person over the age of 40 to have won a UFC championship fight, having done so four times.^{[citation needed]}

Couture was an Olympic wrestling alternate and has lived in Corvallis, Oregon, throughout much of his career, where he served as an assistant wrestling coach and a strength and conditioning coach for Oregon State University. He established Team Quest with Matt Lindland and Dan Henderson, a training camp for fighters, based out of Gresham, Oregon, and headed by coach Robert Folis. In 2005, Couture moved to Las Vegas, where he opened his own extensive chain of gyms under the name Xtreme Couture. He currently trains at his Las Vegas-based gym. Couture partnered with Bas Rutten in the opening of Legends Gym in Hollywood, California.

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.

Anderson da Silva (Portuguese pronunciation: [ˈɐ̃deʁsõ ˈsiwvɐ]; born April 14, 1975) is a Brazilian mixed martial artist. He is the current UFC Middleweight Champion and the promotion's longest reigning champion. With 14 consecutive wins and 9 title defenses, Silva holds the longest winning streak and title defense streak in UFC history.

Silva is ranked as the number one Middleweight in the world by multiple publications, and is the consensus No. 1 pound-for-pound fighter in the world according to ESPN, Sherdog, Yahoo! Sports, MMAFighting.com and other publications. UFC president Dana White has proclaimed Silva as "the greatest mixed martial artist ever."^{[undue weight? – discuss]} Silva is also the last Cage Rage Middleweight Champion and a former Shooto Middleweight Champion. Besides the UFC and Cage Rage, Silva has fought for a number of other MMA promotions including the Pride Fighting Championships, Shooto and Rumble on the Rock.

Although known primarily for his mastery of Muay Thai striking, Silva is also a Brazilian Jiu-Jitsu blackbelt, a rank he earned in 2006 from Antônio Rodrigo Nogueira who follows Gracie Lineage through Carlson Gracie, like Murilo Bustamante and the Brazilian Top Team. He began martial arts training at the age of 14, training Tae kwon do and earning a black belt by the age of 18. He is also a black belt in Judo and a yellow rope in Capoeira.